Received in revised form 10 December 2015 Accepted 30 December 2015
Available online 12 January 2016
Evapotranspiration (ET) mapping at the Landsat spatial resolution (100 m) is essential to fully understand wateruse and water availability at the ﬁeld scale. Wateruse estimates in the ColoradoRiverBasin (CRB), which has di- verse ecosystems and complex hydro-climatic regions, will be helpful to water planners and managers. Availabil- ity of Landsat8 images, starting in 2013, provides the opportunity to map ET in the CRB to assess spatial distribution and patterns of wateruse. The Operational Simpliﬁed Surface Energy Balance (SSEBop) model was used with 528 Landsat8 images to create seamless monthly and annual ET estimates at the inherent 100 m ther- mal band resolution. Annual ET values were summarized by land use/land cover classes. Croplands were the larg- est consumer of “blue” water while shrublands consumed the most “green” water. Validation using eddy covariance (EC) ﬂux towers and water balance approaches showed good accuracy levels with R 2 ranging from 0.74 to 0.95 and the Nash–Sutcliffe model efﬁciency coefﬁcient ranging from 0.66 to 0.91. The root mean square error (and percent bias) ranged from 0.48 mm (13%) to 0.60 mm (22%) for daily (days of satellite overpass) ET and from 7.75 mm (2%) to 13.04 mm (35%) for monthly ET. The spatial and temporal distribution of ET indicates the utility of Landsat8 for providing important information about ET dynamics across the landscape. Annual crop wateruse was estimated for ﬁve selected irrigation districts in the Lower CRB where annual ET per district ranged between 681 mm to 772 mm. Annual ET by crop type over the Maricopa Stanﬁeld irrigation district ranged from a low of 384 mm for durum wheat to a high of 990 mm for alfalfa ﬁelds. A rainfall analysis over the ﬁve districts suggested that, on average, 69% of the annual ET was met by irrigation. Although the enhanced cloud-masking capability of Landsat8 based on the cirrus band and utilization of the Fmask algorithm improved the removal of contaminated pixels, the ability to reliably estimate ET over clouded areas remains an important challenge. Overall, the performance of Landsat8 based ET compared to available EC datasets and water balance estimates for a complex basin such as the CRB demonstrates the potential of using Landsat8 for annual wateruse estima- tion at a national scale. Future efforts will focus on (a) use of consistent methodology across years, (b) integration of multiple sensors to maximize images used, and (c) employing cloud-computing platforms for large scale processing capabilities.
Details of the bias correction and downscaling approach used to translate GCM output into VIC input are reported in Wood et al. (2002, 2004) and Maurer (2007). In brief, the method downscales monthly simulated and observed tem- perature and precipitation probabilities at the GCM spatial scale (regridded to a common 2 degrees latitude by longitude spatial resolution) to the 1/8 degree resolution at which the VIC hydrology model was applied through use of a probabil- ity mapping procedure that is “trained” to monthly empirical probability distributions of the climate model output for cur- rent climate conditions to equivalent space-time aggregates of the gridded (one-eighth degree spatial resolution) obser- vation set of Maurer et al. (2002). The climate model signal was then temporally and spatially disaggregated through use of a resampling approach to create a daily forcing time series for the hydrology model at the same one-eighth degree spa- tial resolution. This method facilitates investigation of the implications of the true transient nature of climate warming as opposed to the more common methods employed where decadal temperature and precipitation shifts are averaged to give a step-wise evolution of climate (e.g. Hamlet and Letten- maier, 1999). It should be noted that the bias correction and downscaling technique that we used by construct reproduce observed climatologies in the special case where the GCM runs have no precipitation and temperature change.
In the 1990s, land-use and land-cover change research promoted by major international organizations entered a stage of unprecedented prosperity and became the focus of global environmental and sustainable development issues [7,8] . Verburg et al.  used a land use change model and a world economic integration evaluation model to simulate changes in agricultural land use in 25 European countries, analyzing its driving forces, mechanisms and factors. Tong et al.  studied the impacts of climate change and land use change on water resources in the small Miami RiverBasin in the USA using CA-Markov and HSPF models. Tao et al.  used SWAT model to assess the impacts of different land use scenarios on hydrological processes in the Fuhe watershed in Poyang Lake Basin (China) and showed that forest land has a higher capacity to conserve the water as compared to pasture land. Rosa et al.  used land use change model, analyzing the assessment of indirect land use change effects and showed that causal-descriptive models appear more suitable for long-term assessments in land use change context while the compared economic models are more suitable for short/medium-term assessments of land use change consequences. The study of land use change in China has mainly focused on the spatiotemporal change process, driving mechanisms and environmental effect  . Tang et al.  systematically summarized the new progress in the theory, method and practical application of the land use/cover change model in China and internationally, and identified problems that need to be solved. Liao et al.  used a geographic information system and topographic mapping and remote sensing image data to study land use changes in a coastal zone and to explore land-sea interactions. Zhao et al.  analyzed the land use/cover change process and the ecological environment effect of these changes in the Tarim River mainstream area of Xinjiang. Zhang and Zhao  studied the temporal and spatial characteristics of land use/cover change in the Yellow River Delta, and quantitatively analyzed the driving factors. Liu et al.  analyzed the temporal and spatial pattern of land-use
for the Next Generation. As part of our research we conducted a survey of college students to understand their generation’s priorities when it comes to addressing the stresses facing the Basin, as well as their preferred solutions to such challenges (what we call the “college age survey”). The cooperation of faculty around the Basin in focusing their students’ attention to the Basin issues and encouraging them to take the anonymous college age survey has been essen- tial and is appreciated. We also have carefully reviewed a survey taken by a group of experts about the Basin (what we call the “water experts survey”) so that a comparison of attitudes by age and background can be made. Results of the college age survey have been used to help repre- sent the attitudes, values and priorities of young people in the future management of the ColoradoRiverBasin.
Water demands in this study were based on the USBR’s Multi-Species Conservation 10
Program (MSCP) (USDOI, 2000) baseline demands for year 2000. Upper Basin de- mands were fixed at 5.2 BCM/yr and Lower Basin at their full entitlement of 9.2 BCM/yr. Although demands will likely increase as population increases in the basin, holding demands steady allows us to isolate the effects climate change from the confounding effects of transient demand increase. CRRM represents withdrawals from the river at 15
groundwater levels and storage may help to develop better plans for maintaining balanced ecosystems, sustainable economic development and encountering the water stress [ 10 ].
Routine monitoring of groundwater from regional to continental scale with the networks of monitoring well is tedious, time-consuming, and expensive. The inconsistency in data collection at the temporal scale, scarce of evenly distributed monitoring wells, the complicated subsurface physical properties, and recharging processes make the groundwater head estimation more complicated. Sometimes to access the hydrological data is restricted by the law enforcement agency. Since 1970s scientists are working on satellite-based remote-sensing systems for measuring hydrological component; groundwater is the latest addition on that [ 11 ]. Avoiding aforementioned challenges, National Aeronautics and Space Administration (NASA)’s twin Gravity Recovery and Climate Experiment (GRACE) mission provides the first opportunity to directly measure groundwater changes from space through the accurate estimation of Earth’s gravity field variations over time and space [ 12 – 14 ]. Unlike traditional remote sensors utilizing electromagnetic emissions, GRACE uses K-Band microwave to estimate inter-satellite drift due to the gravitational force, the effect of the redistribution of earth mass component including cryosphere, hydrosphere, ocean, atmosphere, and land surface within the accuracy of a micrometer. The GRACE data is processed with numerical models to truncate the effect of atmospheric and oceanic contributions. Therefore, GRACE-observed mass changes mostly reflect terrestrial water storage (TWS), vertical integration of groundwater, soil moisture (SM), surface water (SW), snow water, and vegetation water measurements. Removing the change in surface water storage from GRACE gravity measurements yields an estimated change in groundwater [ 6 , 15 – 18 ]. GRACE provides groundwater level variability relative to the user-defined time baseline instead of an optimal value of groundwater level from the surface or any datum. GRACE-derived GWS demonstrated higher potential to represent the in-situ groundwater-level [ 18 – 21 ]. Many studies have already quantified groundwater variability from GRACE gravity measurements [ 22 – 24 ].
Chapter 3 presented a spectral domain stochastic streamflow simulation tool for data with non-stationary spectral properties. From analysis of flow data in the ColoradoRiverBasin, key variability scales were noted and failed to be reproduced by traditional stochastic methods. Thus, the approach developed utilizes the wavelet transform to identify and model key variability features individually, such that the global and local wavelet spectra are reproduced. Other statistical measures of the historical data such as mean, variance, etc. were also well captured by the simulations. Last, by coupling this method with the disaggregation of chapter 2, spectral properties of upstream locations from Lees Ferry were reproduced without any additional conditioning. As the periodic spectral components were simulated with auto-regressive models, an underlying assumption of normality was implied. While this is not exactly the case for streamflow at Lees Ferry, the ability to accurately simulate the time-evolution of variability modes likely outweighs this drawback.
Abstract. The study presents an approach to represent the two first order moments of temporal runoff variability as a function of catchment area and aggregation time interval, and to map them in space. The problem is divided into two steps. First, the first order moment (the long term value) is analysed and mapped applying an interpolation procedure for river runoff. In a second step a simple random model for the river runoff process is proposed for the instantaneous point runoff normalised with respect to the long term mean. From this model analytical expressions for the time-space variance- covariance of the inflow to the river network are developed, which then is used to predict how the second order moment varies along rivers from headwaters to the mouth. The obser- vation data are handled by a hydrological information sys- tem, which allows to display the results either in the form of area dependence of moments along the river branches to the basin outlet or as a map of the variation of the moments across the basin. The findings are demonstrated by the ex- ample of the Moselle drainage basin (French part).
A BSTRACT : Côte d'Ivoire, like many African countries, has many construction sites and we can witness the transformation of these cities. Our study is interested in Bondoukou, a city in the northeast of the Côte d'Ivoire which does not escape the major development paths. Through this study we used satellite images to have the characteristics of our study area, the map of the slopes, the digital terrain model and the land use through processing by GIS geographic information systems. We observed in the area variations in altitude between 344 and 437 meters and slopes of the order of 0, 5.57, 11.1 and 16.07 degrees. We could thus distinguish an urbanized area, an area of bare soil, an area of vegetation and an area of watercourses. Openstreetmap data was useful for us to check the consistency of our results and validate them.
understanding the hydrologic cycle and impacts of water diversion, storage, and use at local, regional, and global scales. Within the last several decades, there have been great advances in our ability to compute and map ET over large areas through the use of satellite-based remote sensing and geospatial models. The NASA Applied Sciences Program Water Resources Application Area and the World Bank are co-sponsoring the 2015 International Workshop on EvapotranspirationMapping for Water Security to further advance the use of these ET tools. The workshop is free and open to the water resources community, but registration is limited to 150 participants.
Erosion and Salinity are two of the most significant environmental problems impacting on agricultural lands in Australia. Currently 48000 hectares of Queensland are seriously affected by salinity, and an estimated 3100000 hectares of Queensland are also likely to be affected by the year 2050 (Gordon, I. 2002). When this is combined with approximately 20 to 60 tonnes of top soil per hectare being lost from cropping areas on an annual basis (Carey, B, Harris, P. 2001), it has become apparent that action needs to be taken. Through instigating efficient land management practices we must aim to prevent the formation of saline soils and water ways and at the same time limit the loss of top-soil through erosion.
energy – desalination offers an appealing component for each nation’s scheme of overall water independence. Indeed, many of the parties involved are considering pursuing desalination proliferation (Hoff et al. 731); Israel has already developed facilities that can produce up to 250 MCM annually (Hoff et al. 720). Israel’s desalination regime, currently reportedly supplying for 50% of the drinking water consumed in the country, is projected to reach 700 MCM per year by 2020, satisfying 70% percent of drinking water demands (Schwartzstein). While these numbers are promising, it is only through great expense and rigorous construction schedules that Israel has achieved this standard, and the other nations in the basin are not as rich as Israel. To progress from having next to no desalination capabilities to an ability to account for a significant portion of a nation’s supply is an undertaking that will require time and (potentially outside) money, especially in the case of Palestine. Being the most costly water production option presented thus far, both in terms of installation and upkeep, as well as one of the models with the longest delays before producing a significant supply, it would be a tough sell to convince leaders outside of Israel that desalination should be selected as the primary source of water supply in the near future, and sought after aggressively, as the Israelis have done.
A central question in our study is how well VIC captures the variability in hydrologic storage for the ColoradoRiverbasin. This is not unlike a more traditional problem in wa- ter resources, which is how well a reservoir’s stage-storage relationship captures the variability in its contents. Lang- bein (1960) addressed such a question for Lake Mead by carefully comparing changes in reservoir volumes as deter- mined by a stage-storage relationship from a recent bathy- metric survey with changes in volumes as calculated through a water budget of observed inflows and outflows. He found that gains in volume as derived from the water budget ex- ceeded those derived from the stage-storage relationship in wet years, and losses in volume as derived from the water budget exceeded those derived from the stage-storage rela- tionship in dry years, with the magnitudes of the residuals proportional to the changes in volume. He attributed these residual quantities to a “hidden” storage term that was ne- glected in the stage-storage relationship, namely, bank stor- age in the sediment of the reservoir, which he estimated at roughly 3 million acre-feet, as compared to the lake’s usable capacity of 27 million acre-feet at the time. In a similar study, Murdock and Calder (1969) estimated about 6 million acre- feet of bank storage for Lake Powell, which also has a usable capacity of 27 million acre-feet.
The yearly increase in temperature is aided by the increase in winter precipitation seen in the Coloradobasin. A recent study has shown that snowfall in the ColoradoBasin has increased from 1042 cm to 1239 cm between the years of 1997 and 1999 (Inouye et al., 2000). This increased snowfall helps to insulate the ground below it. The air temperature above the snow layer may fall well below freezing, but the snow at ground level will still remain around the 0° C mark. This effect helps keep the ground from re-freezing as much as it would if it were exposed directly to the air. As yearly snowfall increases, the ground becomes more insulated from the cold air, and allows for the ground to thaw more deeply than in previous years. This effect helps to exaggerate the active layer thickening that is already occurring as a response to global
longest uninterrupted data set available. The Landsat satellites’ main mission is to image the land areas of the earth and therefore there are typically no open ocean (case 1 water) images available. This is one of the reason why Landsat satellites have been underestimated by the ocean color community for the study of water bodies. In addition, the Landsat instruments have generally had broad bands and low signal-to-noise ratio (SNR) when compared to her- itage ocean color satellites such as SeaWiFS and MODIS. Carrying two instruments onboard, the Operational Land Imager (OLI) and the Thermal InfraRed Scanner (TIRS), Landsat8 is the first of a new generation of Landsat satellites with state-of-the-art technology (Irons et al., 2012). Since its launch in 2013, the OLI instrument onboard Landsat8 has created high expectations in the ocean color community. With its 12-bit quantization and improved SNR, OLI is a big improvement to the Landsat mission. In addition, OLI includes a new coastal band that increased the spectral resolution of the instrument. These improvements are the main drivers to hypothesize that the Landsat8 satellite will have a better performance in water quality studies than its predecessors. Roy et al. (2014) stated this potential use of Landsat8 for fresh and coastal water studies, mainly due to a reported SNR that exceeded expectations and the new coastal band. Therefore, the overall objective of this research is to investigate the performance of Landsat8 for accurately retrieving water constituents.
Sectorial wateruse trends in the Pearl River Delta
Global wateruse has grown at twice the rate of population growth since 1900, amongst others because of urbanization, industrialization and changing life styles (Watkins et al. 2006). By decreasing water retention capacity and water quality, cities reduce water availability. The expansion of urban areas transforms vegetated covers to sealed concrete surfaces. These changes increase surface runoff (Semadeni-Davies et al. 2008), alter the impact of precipitation on the water balance, change the fluxes of evapotranspiration and groundwater recharge, and thus affect surface hydrology and reduce water retention capacity in the urban area (Poelmans et al. 2010). In addition, cities discharge massive amounts of pollutants. Especially nutrients and sediments associated with domestic and industrial activities compromise water quality in both surface flows and groundwater (Groffman et al. 2003, Hatt et al. 2004, Paul and Meyer 2001, Walsh et al. 2005). At the same time, urbanization alters the temporal and spatial distribution of water uses by changing the population distribution and land use patterns. How to match changing water uses with water availabilities is therefore a key challenge for sustainable water resource management in any heavily urbanized region.
and the mining industry (4.3 × 10 8 m 3 ), respectively equal- ing 48.8, 41.4, and 6.7 % of the total change in E(1B). The E(1B) of the other seven sectors declined; the biggest declines were in real estate and renting (−1.6 × 10 8 m 3 ), the financial sector ( − 6.4 × 10 7 m 3 ), and food and tobacco ( − 6.1 × 10 7 m 3 ), equaling − 2.6, − 1.0, and − 1.0 % of the total change in E(1B). E(1B) made different contribu- tions to the WF changes in different sectors. E(1B) in the sectors of wood, paper, and others (725.2 %); electricity, heat, and water (479.9 %); and non-metallic mineral prod- ucts (82.9 %) made greater proportional contributions to the WF increase than E(1B) in other sectors; and E(1B) in textile, clothing, and leather products ( − 96.0 %); the finan- cial sector ( − 73.2 %); and real estate and renting ( − 34.7 %) made greater proportional contributions to decreasing their WFs. The economic structural effect, which includes the pro- portion of sectors, demand pattern change, price leverage, change of intermediate products, and economized material input caused by management improvement, reflects the im- pact of industrial restructuring (Chen and Yang, 2011). From 2002 to 2007, the proportion of the agriculture WF in the total WF grew slightly from 64.5 to 68.0 %, while that of services increased from 6.9 to 10.2 %, and that of the man- ufacturing industry declined from 28.6 to 21.8 %. This may relate to the Beijing Olympic Games in 2008, for which the government made a series of industrial restructurings in the HRB. To decrease the WF, industrial restructuring to cre- ate more efficient water savings should be undertaken by the government and companies.
Global dimming and brightening is one of the most important issues in the field of climate change (Alpert et al., 2005; Streets et al., 2006; Wild, 2009). In this study, variations of solar radiation in Hai Riverbasin fit the pattern of global dimming and brightening. However, the change in sunshine duration, which shows always dimming from 1960 to 2012, does not corresponding with the change in solar radiation. There are so few stations with solar radiation records that their average variation could not be used represent conditions of the whole region. Another possible reason is that change of sunshine duration is not in thorough agreement with that of solar radiation at each station, especially during the period 1990 to 2012. Moreover, variation of sunshine duration in this study is not consistent with that in the Yangtze Riverbasin of China (Zhang et al., 2012). It is suggested that further investigation be conducted on the complex feedback mechanisms between solar radiation and sunshine duration.
et al., 2011 ).
In comparison to the stations on the main Mekong, model per- formance for the Chi and Mun tributaries is relatively poor, although the short duration of observations (especially for Ubon) should be noted. Results are sensitive to the version of UDel pre- cipitation employed, a ﬁnding that was not replicated for the other stations (results for these stations are based on V1.01 for 1991–1996 and V1.02 for 1997–1998). UDel V1.01 leads to a large over estimation of discharge at Yasothon and low NSE and r values ( Table 4 ). The latter are improved by using UDel V1.02 whilst Dv values suggest discharge underestimation (albeit by a smaller amount compared to overestimations for UDel V1.01). Similar differences are evident in results for the Mun. This adds support to the assertion that issues identiﬁed during calibration of the models for these stations may lie, at least in part, with the meteorological data for this part of the catchment. As noted above, the use of alternative gridded precipitation datasets such as CRU will be required to assess the impact of this potential source of uncertainty.