Small Hydro Resource Mapping in Vietnam
W
ORKING
R
EPORT ON THE
D
ESIGN
OF THE
GIS
D
ATABASE
This report was prepared by Gesto Energy Consulting, under contract to The World Bank.
It is one of several outputs from the wind Renewable Energy
Resource Mapping and Geospatial Planning Vietnam [Project ID: P145513]. This activity is funded and supported by the Energy Sector Management Assistance Program (ESMAP), a multi-donor trust fund administered by The World Bank, under a global initiative on Renewable Energy Resource Mapping. Further details on the initiative can be obtained from the ESMAP website.
This document is an interim output from the above-mentioned project. Users are strongly advised to exercise caution when utilizing the information and data contained, as this has not been subject to full peer review. The final, validated, peer reviewed output from this project will be a Vietnam Small Hydro Atlas, which will be published once the project is completed.
Copyright © 2015 International Bank for Reconstruction and Development / THE WORLD BANK Washington DC 20433
Telephone: +1-202-473-1000 Internet: www.worldbank.org
This work is a product of the consultants listed, and not of World Bank staff. The findings, interpretations, and conclusions expressed in this work do not necessarily reflect the views of The World Bank, its Board of Executive Directors, or the governments they represent.
The World Bank does not guarantee the accuracy of the data included in this work and accept no responsibility for any consequence of their use. The boundaries, colors, denominations, and other information shown on any map in this work do not imply any judgment on the part of The World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries.
The material in this work is subject to copyright. Because The World Bank encourages dissemination of its knowledge, this work may be reproduced, in whole or in part, for non-commercial purposes as long as full attribution to this work is given. Any queries on rights and licenses, including subsidiary rights, should be addressed to World Bank Publications, The World Bank Group, 1818 H Street NW, Washington, DC 20433, USA; fax: +1-202-522-2625; e-mail: [email protected]. Furthermore, the ESMAP Program Manager would appreciate receiving a copy of the publication that uses this publication for its source sent in care of the address above, or to [email protected].
SMALL HYDROPOWER MAPPING AND PLANNING
VIETNAM
PROJECT ID: P145513
WORKING REPORT ON THE DESIGN OF THE
SHP GIS DATABASE
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TABLE OF CONTENTS
1 FOREWORD ... 1
2 INTRODUCTION ... 3
3 COLLECTING TEMPORAL DATA ... 5
3.1 RAINFALL GAUGES ... 5
3.2 RUNOFF GAUGES ... 6
3.3 IN-SITU DAM MEASUREMENTS ... 8
4 ORGANIZING BACKGROUND DATA ... 11
4.1 REMARKS ... 11
4.2 ADMINISTRATIVE BOUNDARIES ... 11
4.3 POPULATION AND SETTLEMENTS ... 13
4.4 MAP OF ROADS ... 13
4.5 LAND COVER ... 14
4.6 RIVERS AND WATER STREAMS ... 15
4.7 ELECTRIC GRID ... 15
5 INFORMATION ON HYDROPOWER PROJECTS ... 17
5.1 GENERAL REMARKS ... 17
5.2 GENERAL INFORMATION ON THE PROJECTS ... 17
5.3 RESERVOIR ... 20
5.4 DAM... 22
5.5 SPILLWAY ... 22
5.6 WATERWAY AND POWERHOUSE ... 23
6 RECOMMENDATIONS ... 27
REFERENCES ... 29
ANNEX I – COMPARISON BETWEEN DIFFERENT TYPES OF SOFTWARE ... 31
ANNEX II – MEETING REPORTS ... 36
ANNEX III – COLLECTION OF GLOBAL DATA ... 41
ANNEX IV – STRUCTURE OF THE DATABASE ACCORDING TO THE NATIONAL CONSULTANT ... 54
TABLES Table 2.1 – Main tables that compose the database. ... 4
Table 3.1 – Theoretical sample of a record collected by two rainfall gauges on the Northwestern part of the hydro-meteorological network of Vietnam. ... 5
Table 3.2 – Theoretical daily rainfall depth obtained after processing in situ measurements for two rainfall gauges in the Northwestern part of the Vietnamese hydro meteorological network. ... 6
Table 3.3 – Theoretical sample of a record from two runoff gauges over a period of three consecutive days. The measured variable is the position of the water level at a specific time of the day. ... 7
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Table 3.4 – Theoretical sample of the processed data (mean water flow over a period of 24h) associated with two
distinct runoff gauges (Cua Dat and Khanh Nghia). ... 8
Table 3.5 – Theoretical example of measurements from a seepage meter, a tilt meter and a GPS. This measurements include the water seepage inside the dam, the displacement of a point on the dam and the movement of the surrounding slopes. ... 9
Table 3.6 – Theoretical example of measurements conducted in the reservoir and powerhouse of a dam. Measurements on water flow, water level and energy output. ... 10
Table 4.1 - Administrative boundaries of Vietnam: regions (adapted from GADM) [6]. ... 11
Table 4.2 - Administrative boundaries of Vietnam: sample of provinces (adapted from GADM) [6]. ... 12
Table 4.3 - Administrative boundaries of Vietnam: sample of districts (adapted from GADM) [6]. ... 12
Table 4.4 - Administrative boundaries of Vietnam: communes (adapted from GADM) [6]. ... 12
Table 4.5 – Sample of populations in Vietnam (adapted from GADM, [6]). The acronym lat stands for latitude, long for longitude and pop for population. The field year_pop reads year of count. ... 13
Table 4.6 – Sample of roads and railroads in Vietnam (theoretical example). ... 14
Table 4.7 – Theoretical example of the land cover in Vietnam (adapted from the GeoNetwork database, [7]). . 14
Table 4.8 – Sample of the waterways in Vietnam – rivers and streams (adapted from the GeoFabrik database, [9]). ... 15
Table 4.9 – Theoretical example of sub-stations. The acronym year_of_comiss stands for year of comissinoing and Inst_cap for installed capacity. ... 16
Table 4.10 – Theoretical example of transformers. The acronym year_of_manu stands for year of manufacture, nominal_volt for nominal voltage, nominal_cap for nominal capacity and substn for substation. ... 16
Table 4.11 – Theoretical list of transmission lines. The acronyms P_max and Coef_util stand for maximum power capacity and coefficient of utilization, respectively. ... 16
Table 5.1 – Theoretical sample of hydropower projects in Vietnam: general information. ... 19
Table 5.2 – Theoretical sample of Vietnamese reservoirs and their main features. ... 21
Table 5.3 – Theoretical sample regarding the main features of Vietnamese dams. ... 22
Table 5.4 – Theoretical example of spillways and their respective features. The acronym lat stands for latitude, long for longitude, elev for elevation, dsgn for design, no for number and dim for dimension. ... 23
Table 5.5 –Theoretical sample of Vietnamese waterways, powerhouses and their respective features. The acronym itak stands for intake, ww for waterway, tun for tunnel, srgtk for surgetank, pnstck for penstock, PH for powerhouse, tailrc for tailrace and TML for transmission line. ... 25
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GLOSSARY OF ABBREVIATIONS AND ACRONYMS
ESMAP Energy Sector Management Assistance Program GIS Geographic Information System
GADM Global Administrative Areas GPS Global Positioning System HPP Hydropower Plant
IRDB Irrigation Database
ORDBMS Object-Relational Database Management System VAWR Vietnam Academy for Water Resources
WCS Web Coverage Service WBG World Bank Group WFS Web Feature Service WMS Web Map Service
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1
FOREWORD
The Energy Sector Management Assistance Program (ESMAP) is a global knowledge and technical assistance program administered by The World Bank Group (WBG) and supported by 11 bilateral donors. ESMAP’s efforts focuses on energy security, energy access, and climate change, and take into account three core services: i) analytical work, ii) knowledge clearinghouse, and iii) operational support to The World Bank regions for technical assistance work at the country level.
Carrying out RES mapping and geospatial analysis at country level helps to scale up the deployment of biomass, SHP, solar and wind electricity generation, particularly in countries where one or more of these sources of power are underdeveloped. This is because such mapping is a crucial step to developing a policy framework to guide investment in RES electricity generation which, along with publicly-available data, helps reduce transaction costs and speeds up deployment by providing commercial developers with:
Increased certainty that projects are likely to be approved or permitted with minimal bureaucracy and delay;
Data transparency and a level playing field, thereby reducing barriers to the entry and limiting the scope of corruption;
A baseline of reliable data that can help guide prospecting activities and can be used for data verification purposes;
A better informed off taker or purchasing authority, thereby improving the price negotiation process.
In response, ESMAP has launched a new initiative to support country-driven efforts to improve RES awareness, put in place appropriate policy frameworks for RES development, and provide “open access” to resource and geospatial mapping data. One of the key elements of this ESMAP initiative was to select consulting firms and establish framework agreements for the procurement of resource data and mapping services. For the renewable energy mapping based on hydropower, the WBG hired qualified consulting firms with demonstrated capabilities in providing Small Hydro Power resource mapping and related services and an Indefinite Delivery Contract commenced on May 28, 2013, and is expected to end by 2017. The present project, developed under the scope of the ESMAP, is divided in two main activities:
Activity 1 – Advisory services for building up a GIS national database for small hydro; Activity 2 – Developing guidelines for improved planning of small hydro.
This report is included in the first activity and intends to create guidelines that will advise the National Consultant building the GIS database. Therefore this document aims to advise on the general structure of the database, including the definition of the main features of each object of the database (reservoir, dam, waterway etc.).
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The second chapter consists on the introduction together with general remarks on the adopted software to the development of the GIS database.
The third chapter describes the tables that store the several temporal variables collected in in-situ
measurements. These measurements include rainfall depth and river runoff collected by rainfall and runoff gauges. In this chapter measurements related with dam operations and dam safety are also presented, such as water seepage, soil subsidence, vertical displacement etc.
The fourth chapter presents the main tables that concatenate the background spatial data, such as the administrative divisions that include the boundaries of regions, provinces, districts and communes. This chapter also includes a table with the main objects of the electrical grid: the sub-stations with the respective transformers and also the transmission lines. Finally, three more tables are added for storing the rivers and water streams, the different types of roads on the country and also the Vietnamese populations and settlements.
The fifth chapter presents the various tables that store the hydropower projects with the respective components. Regarding this subject three distinct tables were created. These contain the general information on hydropower projects, reservoirs, dams, waterways and powerhouses.
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2
INTRODUCTION
There are several Object-Relational Database Management Systems (ORDBMS) that may be used in order to store and manage information. Among the most common ORDBMS services, a comparison between PostgreSQL, MySQL and SQLite has already been carried out during the Inception Report of the International Consultant (Annex I).
According to the Inception Report carried out by the National Consultant (November 2015), the Operational System of the GIS hydropower database shall be PostgreSQL [1]. According to the same source, PostgreSQL, often simply Postgres, is an object-relational database management system (ORDBMS) with an emphasis on extensibility and on standards-compliance. As a database server, its primary function is to store data securely, supporting best practices, and to allow for retrieval at the request of other software applications. It can handle workloads ranging from small single-machine applications to large Internet-facing applications with many concurrent users (extracted from [1]).
As a complement to the Database Management System, a WebGIS service will also be used so as to publish geographic data on the web. In the future this will allow a network of users to access and edit the information, regardless of the platform, installation and location where they are accessing the content from. In fact the major strength of a WebGIS lies in the fact that it might be accessed through a simple internet browser. A comparison between different WebGIS, regarding their supported input files, advantages and disadvantages is presented in Annex I.
Still according to the Inception Report carried out by the National Consultant, the programming language
C# in combination with open source libraries such as Openlayers and MapServer will allow to develop the
WebGIS. In this case, Openlayers library will allow displaying background maps such as Google Maps and
Bing Maps. On the other hand, the WebGIS Map Server UMN will be used to publish all the contents on the web.
Following several interactions throughout the past months with the Ministry of Industry and Trade, The World Bank Group, and the National Consultant, the Vietnam Academy for Water Resources (VAWR) and a mission by the International Consultant to Hanoi past November (Annex II), it was recommended that the future Small Hydropower Database could follow a similar structure to the Irrigation Database (IRDB) developed by the National Consultant in close cooperation with the Ministry of Agriculture and Rural Development (MARD). This database, which was built in the scope of the Natural Disaster Control System
was characterized by a seamless interaction between a WebGIS and an Object-Relation Database Management System.
The IRDB, which may be accessed by any user via http://thuyloivietnam.vn/, stores a large amount of information in what concerns Vietnamese water reservoirs. This information includes the main features of the reservoirs, such as the general information (name of the reservoir, river basin, stage of the project etc.) and also more detailed features (irrigation area, catchment area, dead water level, full supply water level etc.). The database contains also a number of tools that allow the control of RTDM (Real-Time Data
47 VN.2015.R.001.0
Monitoring), such as water level (both measured in reservoirs and runoff gauges), rainfall and water salinity. In the same way as carried for the IRDB, the present database also requires the collection of data in order to be populated.
The current project contains itself tasks for collecting global and local data. While the International Consultant was responsible for collecting global data (Annex III), the National Consultant will collect the local data, such as the features of reservoirs, dams and hydropower plants. Note that, during the several meetings between the participants, it was agreed that the collection of the local data would be carried out in parallel to the development of the database.
Therefore the present report will allow having a clear insight on what the structure of the database will be. Table 2.1 presents the main tables that compose the database. These tables include information on the main features of the objects related with hydropower projects (dams, reservoirs, spillways etc.).
Table 2.1 – Main tables that compose the database.
Table Description
Administrative Divisions It contains region, province, district and commune boundaries Rainfall Gauges Rainfall depth measurements
Run-off Gauges Run-off measurements
In-situ Dam Measurements It contains measurements regarding soil subsidence, vertical dam displacement, water seepage, upstream and downstream water levels, output amount of energy, discharged flow and turbine flow.
Transmission lines It contains information on the voltage of lines, initial and final bus bars, maximum power capacity and also the respective utilization coefficient.
Sub-stations General description of the sub-stations, including the respective status, their input voltage, the year of commissioning and their installed capacity.
Transformers It contains the main features of the transformers of each identified sub-station, such as cooling type, year of manufacturer, nominal capacity and nominal voltage
Rivers and water streams General information on rivers and water streams (name and respective river basin)
Hydropower projects General information on the projects (Installed power capacity, height of the dam, coordinates, status of the project, administrative divisions where it is located etc.)
Dams Information on the type and height of the dam. Elevation, width and length of the respective crest. Spillways Description of spillways, including their coordinates, type, crest elevation, number of spans, number of gates and
dimensions, and also design flood.
Reservoir Main features of the reservoirs (FSWL, FWL, MOL, mean annual precipitation on the watershed, flood discharge flows etc.)
Waterway and powerhouse
Description of the waterways (coordinates of the water intake, elevation, length of the canal, tunnel and penstock etc.) and powerhouses (installed capacity, turbine type and flow, tailrace elevation and transmission lines length and voltage
etc.)
The main tables presented in Table 2.1 were adapted from the Inception Report carried out by the National Consultant (Annex IV). For the sake of simplicity, note that the tables showed along the present report are not exactly the same as the ones defined by the National Consultant. However more fields may be added and removed from these tables.
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3
COLLECTING TEMPORAL DATA
3.1
RAINFALL GAUGES
One of the most important variables when developing hydrologic studies is the mean rainfall on the watershed over a series of years. This variable is obtained by processing the rainfall depth measured over a short period of time (seasons, months, days or even hours) by a rainfall gauge.
The rainfall depth is often measured by recording gauges, which automatically record this variable in short periods of time (down to 1 minute, in some cases). This type of gauge is geared with a bucket that collects rainfall and is then translated into a vertical movement by means of a pen on a chart. However, the rainfall depth may also be measured by nonrecording gauges, in which the rainfall depth is read manually at longer time intervals, usually in remote, sparsely inhabited areas.
After collecting rainfall, there are two types of data that may be stored in tables, raw data and processed data. The first type of data is directly read from the bucket and must be processed before used in any hydrological study. Note that this type of data is not continuous as the bucket must be emptied before reaching its full capacity. However, when storing these two types of data in a table, there is common information that must complement the values of rainfall depth, such as: the gauge identification (name and ID), the hydro-meteorological network and administrative divisions (province, district and communes) where the gauge is located, its respective coordinates and also the time when the data was collected. Table 3.1 presents a theoretical record of rainfall depth collected by two distinct rain gauges (named Binh Lu and Lac Son) over a period of three consecutive days. Note that the table includes all the complementary information – described in the previous paragraph – to the rainfall depth. Also, the header of the columns lat_decdeg, long_decdeg and depth_mm include the units of the variables – decimal degrees, decimal degrees and millimeters, respectively.
Table 3.1 – Theoretical sample of a record collected by two rainfall gauges on the Northwestern part of the hydro-meteorological network of Vietnam.
gauge_id YY_MM_DD hh_mm_ss lat_decdeg long_decdeg gauge_name network province district commune depth_mm rf_58_32 2010_05_10 00_00_00 103,37000 22,19000 Binh Lu Northwest Lai Chau Phong To Binh Lu 98,00 rf_57_10 2010_05_10 00_00_00 105,27000 20,27000 Lac Son Northwest Hoa Binh Lac Son T. T Vu Ban 80,00 rf_58_32 2010_05_10 12_00_00 103,37000 22,19000 Binh Lu Northwest Lai Chau Phong To Binh Lu 101,50 rf_57_10 2010_05_10 12_00_00 105,27000 20,27000 Lac Son Northwest Hoa Binh Lac Son T. T Vu Ban 82,30 rf_58_32 2010_05_11 00_00_00 103,37000 22,19000 Binh Lu Northwest Lai Chau Phong To Binh Lu 2,00 rf_57_10 2010_05_11 00_00_00 105,27000 20,27000 Lac Son Northwest Hoa Binh Lac Son T. T Vu Ban 83,00 rf_58_32 2010_05_11 12_00_00 103,37000 22,19000 Binh Lu Northwest Lai Chau Phong To Binh Lu 3,20 rf_57_10 2010_05_11 12_00_00 105,27000 20,27000 Lac Son Northwest Hoa Binh Lac Son T. T Vu Ban 85,00 rf_58_32 2010_05_12 00_00_00 103,37000 22,19000 Binh Lu Northwest Lai Chau Phong To Binh Lu 6,00 rf_57_10 2010_05_12 00_00_00 105,27000 20,27000 Lac Son Northwest Hoa Binh Lac Son T. T Vu Ban 86,30 rf_58_32 2010_05_12 12_00_00 103,37000 22,19000 Binh Lu Northwest Lai Chau Phong To Binh Lu 9,50 rf_57_10 2010_05_12 12_00_00 105,27000 20,27000 Lac Son Northwest Hoa Binh Lac Son T. T Vu Ban 87,10
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After processing the data presented in Table 3.1, the rainfall depth measured over a period of time multiple to twelve hours may be obtained. Table 3.2 presents the daily rainfall depth collected over a period of 24h starting at 00:00 A.M. of the day defined in the second column. Note that from the same rainfall record presented in Table 3.1, a sub-diary rainfall depth over a period of 12h could also be obtained. In this case, a table with twice as the number of rows in Table 3.2 would be the output.
Table 3.2 – Theoretical daily rainfall depth obtained after processing in situ measurements for two rainfall gauges in the Northwestern part of the Vietnamese hydro meteorological network.
gauge_id YY_MM_DD lat_decdeg long_decdeg gauge_name network province district commune depth_mm rf_58_32 2010_05_10 103,37000 22,19000 Binh Lu Northwest Lai Chau Phong To Binh Lu 5,50 rf_57_10 2010_05_10 105,27000 20,27000 Lac Son Northwest Hoa Binh Lac Son T. T Vu Ban 3,00 rf_58_32 2010_05_11 103,37000 22,19000 Binh Lu Northwest Lai Chau Phong To Binh Lu 4,00 rf_57_10 2010_05_11 105,27000 20,27000 Lac Son Northwest Hoa Binh Lac Son T. T Vu Ban 3,30
3.2
RUNOFF GAUGES
Although this type of device is named runoff gauge, the stream flow rate is not directly recorded, even though this variable is one of the most important in hydrologic studies. Instead, water level is recorded and the stream flow rate is deduced by means of a rating curve [2]. This curve is constructed by plotting successive measurements of the discharge and height of the water level.
The water level may be recorded either manually or automatically. Manual measurements of the water level are made using staff gauges, which use graduated boards set in the water surface. In addition, this variable may also be obtained through the use of sound devices, which measure the time between the emission of the signal and the respective reception at the water surface. However, there are also automatic devices – bubble gauges – that sense the water level by bubbling a continuous stream of gas into the water.
In comparison with rainfall depth, the measured water level (raw data) must also be processed before used in any hydrological study. As described above, the water level is converted into stream flow rate by means of a rating curve. Once again, when storing these two types of data in a table, there is common information that must complement the values of water level/stream flow rate, such as: the gauge identification (name and ID), the river, river basin and administrative divisions (province, district and communes) where the gauge is located, its respective coordinates and also the time when the data was collected.
Table 3.3 presents a theoretical sample of a record (over a period of three consecutive days) from two runoff gauges located in the Northern Central part of the hydrological network of Vietnam. As mentioned above the variable recorded by the runoff gauge is the water level at a specific time of the day.
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Table 3.3 – Theoretical sample of a record from two runoff gauges over a period of three consecutive days. The measured variable is the position of the water level at a specific time of the day.
gauge_id gauge_name lat_decdeg long_decdeg network province district river river_system YY_MM_DD hh_mm_ss wat_level_m
ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_10 00_00_00 1.90 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_10 00_00_00 6.10 ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_10 06_00_00 2.36 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_10 06_00_00 5.70 ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_10 12_00_00 1.65 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_10 12_00_00 5.60 ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_10 18_00_00 1.56 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_10 18_00_00 6.13 ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_11 00_00_00 1.76 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_11 00_00_00 6.02 ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_11 06_00_00 1.52 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_11 06_00_00 6.03 ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_11 12_00_00 1.98 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_11 12_00_00 6.08 ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_11 18_00_00 2.35 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_11 18_00_00 6.13 ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_12 00_00_00 2.56 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_12 00_00_00 6.80 ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_12 06_00_00 2.98 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_12 06_00_00 7.10 ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_12 12_00_00 2.89 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_12 12_00_00 7.15 ro_49_21 Cua Dat 19.88158 105.30771 North Central Thanh Hoa Thuong Xuan Chu Ma 2010_05_12 18_00_00 2.51 ro_45_14 Khanh Nghia 19.39033 105.32315 North Central Nghe Tinh Nghia Dan Con Lam 2010_05_12 18_00_00 7.05
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In order to convert the water level to flow stream rate, it is necessary to obtain a rating curve for the respective water course. In the present example let’s admit the two following rating curves for gauges
Cua Dat and Khanh Nghia, respectively:
𝑄 = 24,28 × (ℎ − 0,39)1,25 (1)
𝑄 = 26,36 × (ℎ − 3,25)1,56 (2)
In the two previous equations, the variable ℎ is the measured position of the water surface and 𝑄 is the respective stream flow rate in the water course.
After obtaining the respective stream flow rate for each row of Table 3.3 , the mean water flow over a period of 24h may be obtained by averaging the four values of the flow rate on the same day, Table 3.4.
Table 3.4 – Theoretical sample of the processed data (mean water flow over a period of 24h) associated with two distinct runoff gauges (Cua Dat and Khanh Nghia).
gauge_id gauge_name lat_decdeg long_decdeg network province district river river_system YY_MM_DD flow_m3s ro_49_21 Cua Dat 19,88158 105,30771 North
Central
Thanh Hoa
Thuong
Xuan Chu Ma 2010_05_10 39.82 ro_45_14 Khanh Nghia 19,39033 105,32315 North
Central
Nghe Tinh
Nghia
Dan Con Lam 2010_05_10 119.74 ro_49_21 Cua Dat 19,88158 105,30771 North
Central
Thanh Hoa
Thuong
Xuan Chu Ma 2010_05_11 40.98 ro_45_14 Khanh Nghia 19,39033 105,32315 North
Central
Nghe Tinh
Nghia
Dan Con Lam 2010_05_11 132.49 ro_49_21 Cua Dat 19,88158 105,30771 North
Central
Thanh Hoa
Thuong
Xuan Chu Ma 2010_05_12 70.54 ro_45_14 Khanh Nghia 19,39033 105,32315 North
Central
Nghe Tinh
Nghia
Dan Con Lam 2010_05_12 209.50
3.3
IN-SITU
DAM MEASUREMENTS
Monitoring a dam and its respective components is a critical step when it comes to maintaining a safe infrastructure. The most common causes of dam failure include structural problems and piping (internal erosion due to seepage). In fact both these problems may be overcome with an effective monitoring program, which detects these causes in an early stage so that they can be properly repaired or mitigated. Due to the number of factors involved (hydrological, geotechnical, structural, and power related), a wide variety of measurements are required for dams. These cover everything from the structure of the dam, to the dam's foundation, to the water in the reservoir.
In hydrology, seepage flow refers to the flow of a fluid (water) in permeable soil layers such as sand. The fluid fills the pores in the unsaturated bottom layer and moves into the deeper layers as a result of the effect of gravity. The soil has to be permeable so that the seepage water is not stored [3]. This variable may be recorded with simple seepage meters that consist in a chamber (with a bag detached) placed on the submerged sediment soil. The change in volume during the time the bag was attached to the chamber is the volumetric rate of flow through the part of the bed. However, more sophisticated methods are used when monitoring seepage on dams, such as the v-notch weir. In this method a drain coming out of the
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dam is connected to a v-notch weir that allows the measurement of water flow rate as a function of the depth of the water in relation to the V crotch. The reason for using this type of sections (instead of a simple rectangular section) is the fact that a change in the flow rate has a large change in the depth allowing more accurate head measurement than with a rectangular weir [4].
Monitoring slope movements can evaluate the stability of slopes and give people a pre-warning before failure. One of the most potentially valuable instruments though not yet widely used to measure the internal movements for earth dam is the portable tilt meter of electrical type. This device is provided with an accelerometer transducer. A measurement is made by placing the tilt meter in an exactly reproducible position on a reference plate [4].
Table 3.5 presents a sample of measurements from different types of instruments: a seepage meter (SM), a tilt meter (TM) and a GPS.
Table 3.5 – Theoretical example of measurements from a seepage meter, a tilt meter and a GPS. This measurements include the water seepage inside the dam, the displacement of a point on the dam and the
movement of the surrounding slopes.
inst_ID YY_MM_DD hh_mm_ss seepage_mmday displacement_mm subsidence_mm dam_ID
SM_01_12 2010_05_10 12_00_00 0.02 - - DM_01_09 TM_09_01 2010_05_10 12_00_00 - - 0.20 - DM_01_09 GPS_08_18 2010_05_10 12_00_00 - - - 1.50 DM_01_09 SM_01_12 2010_06_10 12_00_00 0.04 - - DM_01_09 TM_09_01 2010_06_10 12_00_00 - - 0.50 - DM_01_09 GPS_08_18 2010_06_10 12_00_00 - - - 5.00 DM_01_09
In addition, it is also important to monitor the water level in the reservoir and the downstream pool regularly in order to estimate the stored volume of water in the reservoir together with its respective level in relation to the regular outlet works and emergency spillway. Also, from the water level in the reservoir it is possible to estimate the water flow discharged through the spillway or through the bottom outlet of a dam [5].
Table 3.6 includes a sample of the measurements regarding turbine and discharge flow (fields
turb_flow_m3s and disch_flow_m3s, respectively), water levels, both upstream and downstream (fields
upstrm_level_m and dwnstrm_level_m, respectively), and also the instantaneous energy output
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Table 3.6 – Theoretical example of measurements conducted in the reservoir and powerhouse of a dam. Measurements on water flow, water level and energy output.
inst_ID YY_MM_DD hh_mm_ss upstrm_level_m dwnstrm_level_m turb_flow_m3s disch_flow_m3s out_E_MW dam_ID
SG_02_12 2010_05_10 00_00_00 505.2 - - 50 - DM_02_03 SG_02_12 2010_05_10 04_00_00 503.0 - - 40 - DM_02_03 SG_02_12 2010_05_10 08_00_00 502.0 - - 35 - DM_02_03 SG_02_13 2010_05_10 00_00_00 - 424.6 - - - DM_02_03 SG_02_13 2010_05_10 04_00_00 - 424.1 - - - DM_02_03 SG_02_13 2010_05_10 08_00_00 - 424.0 - - - DM_02_03 FM_02_10 2010_05_10 00_00_00 - - 35.0 - - DM_02_03 FM_02_10 2010_05_10 04_00_00 - - 34.5 - - DM_02_03 FM_02_11 2010_05_10 08_00_00 - - 34.3 - - DM_02_03 PM_02_05 2010_05_10 00_00_00 - - - - 248.0 DM_02_03 PM_02_05 2010_05_10 04_00_00 - - - - 237.8 DM_02_03 PM_02_05 2010_05_10 08_00_00 - - - - 233.4 DM_02_03
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4
ORGANIZING BACKGROUND DATA
4.1
REMARKS
As stated previously, all local datasets shall be gathered by the National Consultant. Data coming from local (usually official) sources should always be preferable when compared with data from other sources, such as globally available data.
Nonetheless, the International Consultant already conducted a complementary compilation of readily available global geographic data for Vietnam, which might be used in the event that any of the local data is not available. In fact this task was preliminary presented in the Inception Report carried out by the International Consultant.
Considering the past experience of the International Consultant, the types and sources of globally available datasets with relevance to the project are presented in Annex II.
4.2
ADMINISTRATIVE BOUNDARIES
In order to ease the spatial analysis of data, it is common to include administrative boundaries in geospatial databases. For this purpose there are several global data sources available online, such as the
Global Administrative Areas (GADM) [6]. Note than it is common to build an individual table for each level of administrative boundaries of a given country. For Vietnam, GADM includes four separate tables for regions, provinces, districts and communes all over the country. It would be also possible to store one table containing the communes of Vietnam, which would then be filtered before imported to a GIS system. However such practice could lead to unnecessary management of large amounts of information in case the user only interacted with large scale administrative divisions.
Table 4.1 concatenates the 8 regions of Vietnam together with the respective identification – ID_1. Therefore, NAME_0 corresponds to the name of the country and the index 1 represents regions.
Table 4.1 - Administrative boundaries of Vietnam: regions (adapted from GADM) [6].
NAME_0 ID_1 NAME_1 TYPE_1
Vietnam 1 Mekong River Delta Region Vietnam 2 Red River Delta Region Vietnam 3 North East Region Vietnam 4 South East Region Vietnam 5 North Central Coast Region Vietnam 6 South Central Coast Region Vietnam 7 North West Region Vietnam 8 Central Highlands Region
On the other hand, Table 4.2 presents a sample of provinces in Vietnam – field NAME_2 – together with the respective identification – ID_2 –, where the index 2 represents provinces.
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Table 4.2 - Administrative boundaries of Vietnam: sample of provinces (adapted from GADM) [6].
NAME_0 ID_1 NAME_1 ID_2 NAME_2 TYPE_2
Vietnam 1 Mekong River Delta 2 An Giang Province Vietnam 3 North East 25 Bac Giang Province Vietnam 3 North East 26 Bac Kan|Bac Can Province Vietnam 1 Mekong River Delta 3 Bac Lieu Province Vietnam 2 Red River Delta 14 Bac Ninh Province Vietnam 1 Mekong River Delta 4 Ben Tre Province Vietnam 4 South East 37 Ba Ria - VTau|Ba Ria-Vung Tau Province Vietnam 6 South Central Coast 51 Binh Dinh Province Vietnam 4 South East 38 Binh Duong Province Vietnam 4 South East 39 Binh Phuoc Province
(…)
Also, Table 4.3 presents a sample of the districts of Vietnam – field NAME_3 – together with the respective identification – ID_3 –, where the index 3 stands for districts.
Table 4.3 - Administrative boundaries of Vietnam: sample of districts (adapted from GADM) [6].
NAME_0 ID_1 NAME_1 ID_2 NAME_2 ID_3 NAME_3 TYPE_3
Vietnam 1 Mekong River Delta 2 An Giang 18 Phu Tan District Vietnam 3 North East 25 Bac Giang 244 Son Dong District Vietnam 1 Mekong River Delta 5 Ca Tho 38 Binh Thuy District Vietnam 1 Mekong River Delta 9 Long An 76 Duc Hue District Vietnam 3 North East 33 Thai Nguyen 331 Phu Binh District Vietnam 3 North East 33 Thai Nguyen 332 Phu Luong District Vietnam 4 South East 36 Dong Nai 355 Long Thanh District Vietnam 4 South East 40 Binh Thuan 389 Ham Thuan Nam District Vietnam 5 North Central Coast 45 Nghe An 456 Que Phong District Vietnam 5 North Central Coast 48 Thua Thien - Hue 487 Phu Loc District Vietnam 6 South Central Coast 50 Da Nang City|Da Nang 522 Son Tra District
(…)
Finally, Table 4.4 concatenates all the information mentioned in the previous tables (excluding the field
TYPE_*) together with the name of Vietnamese communes – field NAME_4 – and their identification –
ID_4.
Table 4.4 - Administrative boundaries of Vietnam: communes (adapted from GADM) [6].
NAME_0 ID_1 NAME_1 ID_2 NAME_2 ID_3 NAME_3 ID_4 NAME_4 TYPE_4
Vietnam 1 Mekong River Delta 1 Dong Thap 1 Cao Lanh 13 Hoà An Commune Vietnam 3 North East 27 Cao Bang 269 Trung Khanh 4285 Doan Com Commune Vietnam 5 North Central Coast 47 Quang Tri 480 Vinh Linh 7876 Vinh Son Commune Vietnam 5 North Central Coast 48 Thua Thien - Hue 486 Phong Dien 7981 Phong Son Commune Vietnam 6 South Central Coast 54 Quang Nam 566 Thang Binh 9304 Bình An Commune Vietnam 6 South Central Coast 55 Quang Ngai 569 Ba To 9354 Ba Ði?n Commune
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Vietnam 7 North West 57 Hoa Binh 595 Luong Son 9715 Trung Son Commune Vietnam 7 North West 57 Hoa Binh 596 Lac Son 9743 Van Son Commune Vietnam 8 Central Highlands 62 Gia Lai 648 Kbang 10456 Lo Ku Commune
(…)
4.3
POPULATION AND SETTLEMENTS
The information on settlements and population, respective is capital for the first design approach of HP projects, especially for estimating the power capacity of a HPP.
Table 4.5 presents the general information of a sample of Vietnamese populations, including their coordinates (latitude and longitude), respective administrative divisions where they are located (region, province and commune) and also their number of inhabitants and respective year of count.
Table 4.5 – Sample of populations in Vietnam (adapted from GADM, [6]). The acronym lat stands for latitude,
long for longitude and pop for population. The field year_pop reads year of count.
ID name lat_deg long_deg region province District pop year_pop
pop_54_109 Son Tinh 15,19090 108,74295 South Central Coast Quang Ngai Son Tinh 5000 2015 pop_23_59 Quang Ninh 21,25000 107,33333 North East Quang Ninh Ba Che 9000 2010 pop_12_63 Cat Hai 20,79380 106,99021 Red River Delta Hai Phong Cat Hai 200 2012 pop_22_256 Phuoc Dinh 11,40029 108,89386 South East Ninh Thuan Ninh Phuoc 450 2012 pop_60_369 Ngoc Hien 8,64311 104,97070 Mekong River Delta Ca Mau Ngoc Hien 300 2014
4.4
MAP OF ROADS
The road network in Vietnam is 210,000 km, of which 17,300 km are national roads, 17,450 km are provincial roads, 36,400 km are district roads, and 7,000 km are urban roads. The remaining 131,500 km are rural roads.
In what concerns hydropower projects, rural roads are one of the most important elements when doing a detailed cost analysis. In fact many hydropower projects are located in remote areas where only rural roads areas are available to reach the sites.
It is generally difficult to obtain accurate information about the condition of provincial, district and commune roads and it is highly likely that there are large inter-provincial variations in the condition of local road networks. Nevertheless, provincial fieldwork, and evidence from on-going projects indicate that provincial roads in general are in poor condition. This is corroborated by the fact that, similar to national roads, local government expenditures on local road maintenance do not cover even half of the requirements for an average-condition road network.
Rural roads are no exception. About one quarter of the 83,000 km network is believed to be in good or fair condition and 58% of the provincial roads providing connectivity to the main network are in poor condition.
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Table 4.6 – Sample of roads and railroads in Vietnam (theoretical example).
ID classification phase type condition
rr_961 railroad Not Usable Single Very good rr_086 railroad Operational Single Very good rr_300 railroad Under Construction Single N/A rr_514 railroad Operational Single Very good rr_273 railroad Operational Single Very good rr_284 railroad Under Construction Single N/A rr_304 railroad Operational Single Very good rr_308 railroad Under Construction Unknown N/A rd_201 Road Operational Secondary Route Poor rd_001 Road Under Construction Secondary Route N/A rd_002 Road Operational Secondary Route Not good rd_004 Road Under Construction Secondary Route N/A rd_006 Road Operational Primary Route Very good rd_007 Road Operational Secondary Route Good rd_012 Road Operational Primary Route Very good
4.5
LAND COVER
It is a main concern to list the land cover on the watershed of dams in order to estimate the impacts of the infra-structure in its respective surroundings. Land cover allows quantifying the loss of bio-diversity, fauna (including endemic species) and flora. Also when assessing the environmental impact assessment associated with the construction of a dam, it is important to take into account not only the total flooded area but also the flooded protected areas as these may have a significant impact on local communities. In addition, one must bear in mind that when filling a reservoir there will be a number of infrastructures and roads submerged, beyond all the bio-diversity affected.
Table 4.7 presents a sample of areas (field area) and the respective ecosystem (ecos), type of soil (soil) and mean slope of the area (slp).
Table 4.7 – Theoretical example of the land cover in Vietnam (adapted from the GeoNetwork database, [7]).
ID area ecos soil Slp_%
29 Water - Protected areas Not available Not available Not available 8 Herbaceous - Protected areas Deserts / Polar Regosols 8 to 16 25 Bare areas - Protected areas Deserts / Polar Regosols 5 to 8 24 Bare areas - no use / not managed (Natural) Deserts / Polar Regosols 16 to 30 28 Water - Coastal or no use / not managed (Natural) Not available Not available Not available 30 Water - Inland Fisheries Not available Not available Not available
7 Herbaceous - no use / not managed (Natural) Deserts / Polar Water 2 to 5 (…)
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4.6
RIVERS AND WATER STREAMS
The Vietnamese waterways are managed by the Vietnam Inland Waterways Administration (VIWA), which is under the control of the Ministry of Transport. This governmental organization is responsible for managing the ports, rivers, canals and lakes of Vietnam. Among a number of functions, VIWA has a jurisdiction of more than 6,000km of waterways [8].
Table 4.8 presents a theoretical sample of the Vietnamese waterways, which includes the ID of the river, the name, the river basin (field river_basin) and the type of the waterway (river or stream). Also, in the following table it is important to include the capacity of each hydropower project and the total generation capacity in the river basin.
Note that the field ID contains an identification code in the form of “rv_” (which stands for river) followed by the number of the waterway. In this case, the code does not include any specification regarding the province, as waterways often cross different provinces.
Table 4.8 – Sample of the waterways in Vietnam – rivers and streams (adapted from the GeoFabrik database, [9]).
ID name river_basin type river_cap_MW rvbsn_cap_MW
rv_0001 Song Cau Song Cau river 200 500 rv_0652 Song Cau Do Song Cau Do river 500 1000 rv_0677 Song Ca Lo Song Cau river 100 500 rv_0003 Song Cay Khe Song Kay Khe river 50 100 rv_0674 Song Thu Bon Song Cau Do river 200 1000 rv_0476 Song Chay Song Lo river 20 150 rv_0338 Song Cong Song Cau river 50 500 rv_0510 Suoi Ba Lua Nha Be stream 0 0 rv_0212 Suoi Song Cau Song Dinh stream 0 0
(…)
4.7
ELECTRIC GRID
For the analysis of on-grid hydropower projects it is important to include the national electric grid as part of the database as it allows estimating the cost of the transmission lines that connect the hydropower plant to the respective sub-station. On the other hand it may also be important to identify the available power capacity of the nearest sub-stations.
A substation is a part of an electrical system that transforms voltage from high to low and the reverse. Table 4.9 presents a theoretical sample of sub-stations including their main characteristics, such as the stage of the project (field status of Table 4.9), the year of commissioning (field year_of_comiss), the input and output voltage (field voltage_kv of Table 4.9) and the respective installed capacity (field
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Table 4.9 – Theoretical example of sub-stations. The acronym year_of_comiss stands for year of comissinoing
and Inst_cap for installed capacity.
ID name status year_of_ comiss voltage_kv Inst_cap_MVA
SUB_01 Bin Dinh Operational 2010 66/33 60.0 SUB_02 Ho Chi Minh IX Under Construction 2018 110/22 20.0 SUB_08 Ho Chi Minh IV Operational 2005 220/110 84.0 SUB_14 Bien Hoa I Operational 2002 110/22 12.5 SUB_23 Nha Trang Operational 2000 110/22
220/110 56.0
Also, Table 4.10 presents an example of transformers, whose main function is to change voltage levels between high transmission voltages and lower distribution voltages. This table includes information on the type of cooling of the transformer (field cooling_type of Table 4.10), the year of manufacture (field
year_of_manu of Table 4.10), the nominal voltage and the nominal capacity (field nominal_volt_kv and nominal_cap of Table 4.10).
Table 4.10 – Theoretical example of transformers. The acronym year_of_manu stands for year of manufacture,
nominal_volt for nominal voltage, nominal_cap for nominal capacity and substn for substation.
ID cooling_tyoe year_of_ manu nominal_volt_kv nominal_cap_MVA substn_ID
TRANS_01 OFAF 2009 66/33 60 SUB_01
TRANS_02 OMAN 2017 110/22/6.6 20 SUB_02 TRANS_11 OFAF 2004 220/110/33 84 SUB_08 TRANS_13 OFAF 2002 110/22/6.6 12.5 SUB_23 TRANS_20 OMAN 1998 220/110/18.6 56 SUB_23
Finally, Table 4.11 presents the main features of the transmission lines, which are responsible for carrying power from power sources to demand centers. These features include the initial and final bus bars (fields
Initial_busbar and Final_busbar of Table 4.11), the voltage and the maximum power capacity (fields
voltage_kv and P_max_MW of Table 4.11) and also the coefficient of utilization (field Coef_util_% of Table 4.11).
Table 4.11 – Theoretical list of transmission lines. The acronyms P_max and Coef_util stand for maximum
power capacity andcoefficient of utilization, respectively.
ID type status Initial bus bar Final bus bar voltage_kv P_max_MW Coef_util_%
TML_01 Overhead Operational Bin Dinh Tran Quan Dieu 66 33 75.3 TML_02 Overhead Under Construction Ho Chi Minh Bien Hoa 110 56 62.3 TML_03 Overhead Operational Ho Chi Min Phan Thiet 220 380 84.6 TML_04 Underground Operational Nha Trang Vin Nguyen 220 198 93.6 TML_05 Overhead Operational Chaozou Yangxi 110 79 71.2
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5
INFORMATION ON HYDROPOWER PROJECTS
5.1 GENERAL REMARKS
In what concerns to hydropower (HP) projects, they may be divided in reservoir, dam, water intake/water way and power house. In this present project the database structure regarding HP projects include four different tables:
1. A table with the general information on hydropower projects, outlining their main features, such as coordinates of the dam together with the administrative divisions where it is located, installed capacity, total and unitary costs of the project and the respective affected area;
2. The second table will concatenate the main features of the reservoir, including the respective characteristic water levels (flood level, full still water level and dead level), and the characteristic volumes (volume at the full still water level, gross volume, active volume and dead volume). This table also includes information on the watershed area, mean annual precipitation, annual income flow and flood flow for different return periods.
3. A third table also presents information on the features of the dams, namely their coordinates, type (embankment, gravity, arch or buttress), height, crest elevation, width and length.
4. The last table presents information regarding the water intake and powerhouse. These features include the intake level and the respective coordinates and the dimensions of the trash rack. There will also be information on the waterway (length and slope), surge tank (type and diameter), penstock (length, diameter and lining), forebay (length, width and depth), powerhouse (turbine type, number of units, installed capacity, firm capacity, design height, maximum flow discharge and mean energy output) and tailrace (level, length, width and slope) and transmission lines (voltage and length).
5.2
GENERAL INFORMATION ON THE PROJECTS
As mentioned in 5.1, the table presented in this section includes general information on hydropower projects. Beyond their ID and name, there will be information regarding the province, district, commune and river ID where the projects are located. Once again, the ID of the projects will not only include the number of the project but also the number of the river basin, which means that the ID will be written in the form of:
"hpp_" + river basin ID + "_" + Number of the project
Even though it is possible to repeat the number of the project without repeating the project ID, it is advisable to keep the “Number of the project” unique.
In what concerns the economic indicators of a project, it is advisable not only to include the total cost of the investment but also the unitary costs, such as the ratio between the capital expenditure and the
47 VN.2015.R.001.0
installed capacity (1) and the levelized cost of electricity (4). This indicators allow the expedite comparison between different projects.
𝐶𝑎𝑝𝑒𝑥(𝑉𝑁𝐷/𝑀𝑊) = 𝑇𝑜𝑡𝑎𝑙 𝑖𝑛𝑣𝑒𝑠𝑡𝑚𝑒𝑛𝑡 (𝑉𝑁𝐷)
𝐼𝑛𝑠𝑡𝑎𝑙𝑙𝑒𝑑 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦(𝑀𝑊) (3) 𝐿𝐶𝑂𝐸(𝑉𝑁𝐷/𝑀𝑊ℎ) = 𝑁𝑃𝑉 𝑜𝑓 𝑡𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡𝑠 𝑜𝑣𝑒𝑟 𝑙𝑖𝑓𝑒𝑡𝑖𝑚𝑒 (𝑉𝑁𝐷)
𝑁𝑃𝑉 𝑜𝑓 𝑒𝑙𝑒𝑐𝑡𝑟𝑖𝑐𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑒𝑑 𝑜𝑣𝑒𝑟 𝑙𝑖𝑓𝑒𝑡𝑖𝑚𝑒(𝑀𝑊ℎ) (4)
Where NPV means Net Present Value. Note that the cost of hydropower projects are mainly due to civil works and equipment and may represent up to 90% of the total investment costs.
Other indicators that support the comparison between different projects are the number of people and the area affected by the reservoirs (forest, vegetation etc.) and also required infra-structures as a complement to the projects (such as roads).
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Table 5.1 – Theoretical sample of hydropower projects in Vietnam: general information.
ID name status province district river river_basin capacity_MW break_date developer residence_ha cultiv_ha (…) hpp_01_10 Project 1 In operation An Giang Tan Chau Tien Mekong 505 12_05_2000 EVN 0.0 0.0 (…) hpp_01_11 Project 2 Under Construction Ben Tre Cho Lach Tien Mekong 200 N/A EVN 5.2 1.0 (…) hpp_02_12 Project 3 Feasibility Study Long An Thanh Hoa Vam Co Tay Soai Rap 125 N/A EVN 0.0 3.0 (…) hpp_05_13 Project 4 In operation Ho Chin Minh Cu Chi Sai Gon Soai Rap 15 10_10_2005 IPP 0.0 0.5 (…) hpp_05_14 Project 5 In operation Bac Kan Bach Thong Cau Hong 20 05_03_1998 IPP 10.1 0.8 (…) hpp_10_15 Project 6 Pre-Feasibility Study Binh Phuoc Bu Dop Be Soai Rap 75 N/A EVN 0.0 2.5 (…)
ID (…) forest_ha veget_ha resetled_people afctd_area_ha new_road_km upgd_road_km cost_total_MVND ucost_MVND_MW ucost_MVND_MWh
hpp_01_10 (…) 203.8 50.0 0 250.0 20.0 1.0 25,250,000 50,000 1.4 hpp_01_11 (…) 50.0 29.6 50 85.0 15.0 0.5 19,000,000 95,000 1.9 hpp_02_12 (…) 10.1 12.0 0 25.0 2.0 5.0 10,937,500 87,500 1.4 hpp_05_13 (…) 4.6 9.3 0 13.5 5.2 4.2 975,000 65,000 2.2 hpp_05_14 (…) 3.0 15.8 70 28.8 6.5 5.0 1,550,000 77,500 2.2 hpp_10_15 (…) 12.3 19.0 0 33.5 4.3 2.0 4,968,750 66,250 3.1
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5.3
RESERVOIR
In a general overview, reservoirs are the enlarged artificial lakes created in the upstream part of dams. As both the water inflow and outflow have strong variations during the hydrologic year, so do the volume in the reservoir have. Following these variations of volume there are three distinct water levels (included in Table 5.2) worth to mention:
1. Dead level (DL, field dead_level_m) – Is the level of water below the lowest off-take, meaning that it cannot be managed under normal reservoir operations. The water level under this level is often named as dead volume (field dead_vol_hm3).
2. Full supply level (FSL, field FSL_m) – Corresponds to the maximum operation level of a reservoir and consequently to the total storage capacity of the reservoir. Moreover this is the level of the invert of fixed spillways or the top of the gates when closed. The volume between the dead level and the full supply level is named as active volume (field actv_vol_hm3) [10].
3. Flood level (FL, field flood_level_m) – This is the level at which the spillway reaches its maximum discharge capacity. The difference between the flood level and the dam’s crest elevation is named
freeboard and the volume temporarily stored between the FSL and the FL is the flood-control volume (field flood_vol_hm3).
In what concerns water flows, they may be divided in mean and peak flows. The mean income flow in a watershed often calculated when developing hydrologic studies is the mean annual flowcalculated by averaging the ratio between the runoff volume and the respective elapsed time along a number of years (field income_flow_m3s). This variable takes into account the rainfall in the watershed and also the mean annual evaporation, which is function of the mean annual temperature. Note that there are two distinct methods to calculate the former variable:
1. The empirical formulation of TURC that allows to calculate the mean income flow in the watershed given the mean annual precipitation and temperature [11];
2. In-situ measurements carried out at pour points of watersheds with similar features (area, mean run-off and mean elevation) to the studied watershed.
On the other hand the peak flow (field flood_T500_m3s and flood_T1000_m3s) is also calculated when developing hydrologic studies. In opposition to the mean annual flow, this is often a probabilistic variable obtained through the statistical analysis of water flow measurements. In this case, a statistical formulation (e.g. Goodrich, Pearson or Normal) is fitted to the collected data and hence the peak flow is obtained for a specific return period.
Note that, in comparison to the hydropower project ID presented in 5.2, the reservoir ID (field ID) will also be written in the form of:
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Table 5.2 – Theoretical sample of Vietnamese reservoirs and their main features.
ID hyd_proj_ID reserv_area_ha flood_level_m FSL_m dead_level_m dead_vol_hm3 actv_vol_hm3 gross_vol_hm3 (...) rsv_01_10 hpp_01_10 8,250.6 520.5 514.5 444.5 315.2 220.6 1,260.6 (…) rsv_01_11 hpp_01_11 9,831.1 185.3 182.3 122.3 802.6 561.8 3,210.2 (…) rsv_02_12 hpp_02_12 6,747.8 225.2 222.3 180.3 287.6 201.3 1,150.2 (…) rsv_05_13 hpp_05_13 64.6 320.6 317.4 305.4 2.4 0.0 9.7 (…) rsv_05_14 hpp_05_14 55.9 156.3 153.6 138.6 1.4 0.0 5.6 (…) rsv_10_15 hpp_10_15 1,158.4 203.7 200.7 165.7 134.1 93.8 536.2 (…)
ID (...) flood_vol_hm3 watershed_area_km2 annual_precip_mm income_flow_m3s flood_T500_m3s flood_T1000_m3s
rsv_01_10 (…) 63.0 11,067 1,680 780.7 7,500 16,500 rsv_01_11 (…) 160.5 10,080 1,532 563.5 5,600 11,000 rsv_02_12 (…) 57.5 8,090 1,655 472.6 4,800 10,000 rsv_05_13 (…) 0.5 2,735 1,789 69.8 1,000 2,500 rsv_05_14 (…) 0.3 3,026 1,889 76.4 1,500 3,500 rsv_10_15 (…) 26.8 3,268 1,503 256.9 2,500 5,000
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5.4
DAM
A dam is usually defined as a barrier that allows storing water, either for water supply, generation of energy or even flood control. Their height (field height ofTable 5.3) may vary from a couple of meters to dozens of meters. The top of the dams, usually occupied by roads or other infrastructures, is named as crest. Depending on the dimensions of the dam, the crest varies in terms of elevation (field crest_elev_m
ofTable 5.3), width (field crest_width_m ofTable 5.3), and length (field crest_length_m ofTable 5.3). In what concerts structural design there are four main types of dams:
1. Gravity – This type of structures are usually defined as masses of either masonry or concrete whose stability against sliding and overturning depends on their weight;
2. Arch – The arch dams take advantage from the curvature (both in the horizontal and vertical planes). On the horizontal plane, the forces generated by the mass of water close to the abutments oppose the water pressure on the central part of the dam. On the same way, the mass of water below the vertical curvature of the dam opposes the pressure generated by the mass of water in the upper part of the curvature.
3. Buttress – It consists by a sloping slab supported by a number of spaced buttresses (or counterforts). Usually the formers are triangular masonry or reinforced concrete walls. The membrane (above named as slab) responsible for retaining water may also be replaced by multiple arches, similar to arch dams.
4. Embankment - It is a non-rigid dam that resists the forces on it by its shear strength and to some extent also by its own weight.
In opposition to the reservoirs presented in 5.3, it is common to specify the WGS84 geographic coordinates of the dams in the form of latitude (field Lat (˚)) and longitude (field Long (˚)).
Table 5.3 – Theoretical sample regarding the main features of Vietnamese dams.
ID reserv_ID Lat (˚) Long (˚) dam_type height crest_elev_m crest_width_m crest_length_m
dam_01_10 rsv_01_10 10.84165 105.20989 Concrete gravity 70 73 25.0 305 dam_01_11 rsv_01_11 10.20884 106.15074 Concrete gravity 66 69 22.0 295 dam_02_12 rsv_02_12 10.68217 106.16653 Embankment 50 53 21.5 172 dam_05_13 rsv_05_13 11.05222 106.54657 Embankment 15 18 14.5 420 dam_05_14 rsv_05_14 22.15052 105.90596 Buttress 18 21 15.5 302 dam_10_15 rsv_10_15 11.87964 106.74949 Concrete arch 45 48 18.6 364
5.5
SPILLWAY
One of the most important hydraulic components of dams is the spillway. This element is designed to release the surplus of floodwater when the storage capacity of reservoirs is exceeded. Therefore spillways are considered safety devices in a dam as a valves are in a boiler. Many failures of dams were reported
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due to inadequate capacity or improper design of spillways, especially for earthen and rockfill type dams, which are likely to be destroyed if overtopped.
Spillways may have more than one span (field no_of_spans of Table 5.4), depending on the design flood discharge (stored in the field dsgn_Flood_m3s of Table 5.4) and on the length of the dam crest. Also, their discharge capacity depends on the height of water on top of the spillway crest (whose elevation is stored in the field elev_m of Table 5.4).
Finally, there are a number of spillway types regarding their structural features. Two of the most common types of spillways are the side channel and the Ogee. Regarding the side channel type, as its name suggests the water stored in the reservoir flows into a narrow channel excavated on the side hills towards the abutment of the dam. The Ogee type, usually dam incorporated, has a control weir with a S-shaped profile. This profile was designed to fit to the profile of the lower nappe of a sheet of water falling from a sharp-crested weir. There are other types of spillways, such as the tunnel, drop inlet and the syphon.
In some cases there might be gates to control the release of the water flowing out of the reservoirs. Often there is more than one gate, depending on the number of spans of the spillway (field no_of_gates of Table 5.4). This gates are mostly rectangular and their dimensions are specified in the column gate_dim_bxh of Table 5.4.
Table 5.4 – Theoretical example of spillways and their respective features. The acronym lat stands for latitude,
long for longitude, elev for elevation, dsgn for design, no for number and dim for dimension.
ID hyd_proj_ID lat_deg long_deg type elev_m no_of_spans dsgn_flood_m3s No_of_gates gate_dim_bxh splw_01_10 hpp_01_10 10,83824 105,20804 Side Channel 518,0 3 16500 3 7x3,5 splw_01_11 hpp_01_11 10,20710 106,15020 Ogee 184,0 8 11000 0 N/A splw_02_12 hpp_02_12 10,68110 106,16676 Side Channel 224,0 3 10000 3 6x3 splw_05_13 hpp_05_13 11,05186 106,54632 Syphon 319,0 1 1000 0 N/A splw_05_14 hpp_05_14 22,15241 105,89951 Ogee 155,0 1 1500 0 N/A splw_10_15 hpp_10_15 11,90374 106,80138 Tunnel 202,0 2 5000 2 6x3
5.6
WATERWAY AND POWERHOUSE
The waterway (Table 5.5) of a hydropower project is the hydraulic conveyance system that connects the reservoir to the powerhouse, by means of a canal, tunnel or penstock (field type of Table 5.5). It is common to store the
length of this type of hydraulic components (field ww_length_m, canal_length_m, tun_length_m of Table 5.5) as it allows to estimate costs and also to calculate the head loss associated with friction. Therefore, the waterway must begin with a water intake (whose coordinates are stored in the field itak_lat_deg and
itak_long_deg and whose elevation is defined in the field elevation_m of Table 5.5), which is protected by means of a trash rack.
However, the variation on the water flow released by turbines affects the water flowing in the waterway. In order to overcome this effect, forebays are built upstream the powerhouses, which prevents oscillation of the water level in the waterway [12]. On the other hand, it is also common to build surge tanks (field
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srgtk_type and srgtk_diam_m of Table 5.5) for waterways that include long pressurized components, such as tunnels, where the sudden close of valves will induce a number of followed low and high pressure events. These hydraulic components are reservoirs with several dozens of meters in diameter, which connect to waterways and control the rapid variation of the water level and pressure.
The kinetic energy of water is then converted to electric energy at the powerhouse, by means of a turbine (whose type is stored in the column PH_turb_type and the number of turbines in the field
PH_units_number of Table 5.5) and a generator. When designing a hydropower scheme it is common to calculate the respective installed power capacity (field PH_instcap_MW of Table 5.5 ) through the following equation:
𝑃 = 𝜂 × 𝛾 × 𝑄 × 𝐻 (5)
Where 𝜂 is the efficiency of the turbine, 𝛾 is the specific weight of water, 𝑄 is the design flow (field
PH_dsgn_dischg_m3s of Table 5.5) and 𝐻 is the design water head (field PH_dsgnht_m of Table 5.5). Also, depending on the installed capacity of the hydropower plant and on the number of operating hours (field PH_op_hours _m of Table 5.5), the plant will output a certain amount of energy each year (PH_avg_out_GWh_year of Table 5.5).
After passing through the turbine, the water flows back to the main river. The hydraulic component responsible for sending back the water to the river is the tailrace tunnel or canal (whose length, width and level are presented in fields PH_tailrace_level_m, tailrc_length_m, tailrc_width_m, tailrc_slope).
Finally, the energy generated is transferred to the main electric grid through transmission lines, whose voltage and length is stored in the columns TML_voltage_kV and TML_length_km of Table 5.5.
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Table 5.5 –Theoretical sample of Vietnamese waterways, powerhouses and their respective features. The acronym itak stands for intake, ww for waterway, tun for tunnel, srgtk for surgetank, pnstck for penstock, PH for powerhouse, tailrc for tailrace and TML for transmission line.
waterway_ID type Itak_elevation_m itak_lat_deg itak_long_deg ww_length_m ww_avg_slope tun_length_m canal_length_m pnstck_length_m srgtk_type srgtk_diam_m (...) ww_01_10 Tunnel + penstock 449.5 10.84988 105.21155 15 0.1% 0 0 15 Conical 30.0 – 50.0 (…) ww_01_11 Tunnel + penstock 127.3 10.21813 106.15195 10 0.1% 0 0 10 Simple 40,0 (…)
ww_02_12 penstock 185.3 10.68151 106.16586 250 0.1% 0 0 250 Simple 35.0 (…)
ww_05_13 Canal + penstock 310.4 11.05189 106.54619 6,250 0.1% 550 5,650 50 N/A N/A (…)
ww_05_14 Penstock 143.6 22.15235 105.89940 5,580 0.1% 0 5,530 50 N/A N/A (…)
ww_10_15 Dam incorporated 170.7 11.90397 106.80095 300 0.1% 0 0 300 Spilling 27.0 (…)
waterway_ID (...) pnstck_diam_m pnstck_lining_mm forebay_length_m forebay_dim_bxh_m PH_turb_type PH_units_number PH_instcap_MW PH_firmcap_MW PH_dsgnht_m (...)
ww_01_10 (…) 2x7.2 7 N/A N/A Francis 2 505 202 79.7 (…)
ww_01_11 (…) 7.2 7 N/A N/A Francis 1 200 80 60.0 (…)
ww_02_12 (…) 5.0 5 10 7x4 Francis 1 125 50 42.0 (…)
ww_05_13 (…) 2x3.5 4 10 5x4 Kaplan 1 15 6 34.1 (…)
ww_05_14 (…) 2x4.0 4.5 10 5x4 Kaplan 1 20 8 48.4 (…)
ww_10_15 (…) 4.0 4.5 13 6x4 Francis 1 75 30 64.8 (…)
waterway_ID (...) PH_dsgn_dischg_m3s PH_avg_out_GWh_year PH_op_hours PH_tailrace_level_m tailrc_length_m tailrc_width_m tailrc_slope TML_vo
