Top PDF Land use impact on water quality in two river systems in South Africa

Land use impact on water quality in two river systems in South Africa

Land use impact on water quality in two river systems in South Africa

For purposes of this study the main focus was not on the condition of the estuaries but rather to look at the water quality upstream in the rivers which will ultimately flow into the estuaries, bringing with them any pollutants they may carry. Water quality is a term which can have multiple meanings. In this study water quality refers to variables within the water whose measurements allow us to make assumptions about anthropogenic effects on water. As an overall indicator dissolved major salts (DMS) and electrical conductivity provide an idea of how many salts are suspended in the water. The higher the concentrations the poorer the water quality as it can lead to changes in turbidity and salinisation with a resulting effect on aquatic ecosystem productivity (DEADP, S.a). It should be noted that high concentrations of dissolved major salts and electrical conductivity do not necessarily come from sources of runoff from anthropogenic pollution, but could also be introduced into the system from groundwater. The pH is an important variable as organisms are adapted to survive in a certain optimal pH range (Farrel-Poe 2005), and water is only safe for human use and consumption within a range of about 6.5-8.5 (SDWF S.a). Finally, in order to make more direct assumptions based on anthropogenic effects on water quality, three nutrients were selected which typically have an anthropogenic source and which increase through pollution, application of fertilisers, and untreated human waste - Phosphate (PO 4 ), Nitrate Nitrogen (NO 3 ) and Ammonium Nitrogen (NH 4 ). It has been
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Impact of Land Use Change and Climate Variability on Watershed Hydrology in the Mara River Basin, East Africa

Impact of Land Use Change and Climate Variability on Watershed Hydrology in the Mara River Basin, East Africa

in water extraction from the soil and aquifer by the trees. Trees often have deeper and more extensive rooting systems than other vegetation which enables them to extract groundwater to meet the evapotranspiration demand, especially during the dry seasons when the top soil is dry (Thomas et al., 2012; Doody and Benyon, 2011a; FAO, 2006; Calder, 2005; Benyon et al., 2006). A study by Pinto et al. (2014), for example, estimated that annual soil and groundwater contributions to tree transpiration were about 70% and 30%, respectively. However, during the dry summer months the groundwater contribution became dominant and rose to 73% of transpiration. Additionally, trees have higher aerodynamic roughness than crops that favour higher evapotranspiration rates (Calder, 2005). The differences in leaf, size, shape, thickness, anatomy and chlorophyll content between trees and other plants and even between trees species also affects the rate of transpiration (Muthuri et al., 2009). Consequently, increase in tree cover through agroforestry also increases water use in the watershed in form of evapotranspiration. A study by Muthuri et al. (2004) in central Kenya found that water use in agroforestry systems was higher than for treatments under only maize cultivation. The decrease in groundwater in shallow aquifers, due to increased uptake by trees, decreases the water available and the amount released to the streams as baseflow (Adelana et al., 2015; Fan et al., 2014; Doody and Benyon, 2011b). Generally, the change in baseflow may be either positive or negative depending on the water budget in the aquifer storage (Bruijnzeel, 2004). If the incoming water, as a result of improved infiltration, surpasses the extra water removal by trees, then the extra storage may lead to increase in baseflow. The reverse is also true in the case of negative change in aquifer storage as was the case in our study (Brown et al., 2005; Bruijnzeel, 2004). The overall water yield, which is essentially a summation of surface runoff, lateral flow and groundwater contribution to streamflow, also decreased with an increase in the area under agroforestry.
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Land use change in highland area and its impact on river water quality: a review of case studies in Malaysia

Land use change in highland area and its impact on river water quality: a review of case studies in Malaysia

In Peninsular Malaysia, the main highlands regions in- cluding Upper Perak-Galas, Upper Pergau, Upper Kinta- Jelai, Upper Jelai-Tahan, Upper Selangor-Semantan, and Upper Endau-Rompin (Rozimah and Khairulmaini 2016). Cameron Highlands is the smallest district of Pahang bor- dering Kelantan on the north, Perak on the west, and Lipis district on the south-east (Fig. 1). The total area of Cameron Highlands is 71, 225 ha comprising of three main sub- districts (mukim) which are Hulu Telom (63, 990 ha), Ring- let (5, 165 ha), and Tanah Rata (2070 ha). Cameron High- lands is one of the most famous retreat locations in Malaysia located in the high-elevation central of Titiwangsa Range, where the highest peak is Gunung Irau (2110 m). Approximately, more than 74% of the total area has an elevation of more than 1000 m with a cold climate and scenic landscape. According to Cameron Highlands Local Development Plan (RTD 2018a), almost 29% of the land in Cameron Highland are having steep slopes with a gradient greater than 25° (18,226 ha, 26%) to 35° (2039 ha, 3%). Areas with steep slopes exceeding 25° have a high risk of soil erosion and are not suitable for development (Aminuddin et al. 2001; RTD 2018a). Located in a highland elevation, the average temperature of Cameron Highlands is between 17 ° C and 20 °C all year round. However, the local temperature has risen up to 5 °C in 2014 compared to the past 15 years (RTD 2003). Maximum rainfall (wet season) is during Octo- ber to November and April to May while minimum rainfall (dry season) is during January to March and June to August. There are three main rivers that flow across Cameron High- lands which are the Telom River (37 km) at the north, Ber- tam River (20 km) at the middle, and Lemoi River (16 km) (Fig. 2). All these rivers flow eastward to form the Jelai River
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Implications of Land Use Change on River Flow in South West England

Implications of Land Use Change on River Flow in South West England

Assessing the impacts of future changes in land use on the hydrological cycle is an important issue for the proper management of water resources, since land use changes have implications on both water quantity and quality. Land use changes, in particular the expansion of urban areas, can significantly affect river flow increasing flood risk, whereas, the development of woodland areas could have positive effects on the reduction of peak flow. The present study has been carried out to assess and quantify the impact of land use changes on the water resources of a river basin located in South West England. With this aim, a hydrological model has been applied to some land use scenarios. In particular, two scenarios have been investigated: the first includes the increase of agricultural areas and the decrease of woodlands, the second includes the increase of urban areas and the decrease of woodlands. Results showed that, in the area of study, river flow would likely to be affected by future land use changes, mainly in the case of urban areas increase.
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Impact of Alexandra Township on the water quality of the Jukskei River

Impact of Alexandra Township on the water quality of the Jukskei River

3 (United Nations Database 2005). The rate of population increase is higher than the number of formal houses available for people to live in which makes accommodation a problem in the country’s urban areas. This has resulted in informal settlements developing to meet the demand for accommodation. According to the Department of Housing, in 1989 Gauteng contained 412 000 formal houses in the province’s townships, with 422 000 shacks in their backyards and 635 000 shacks on vacant land. In 2008, 30 % of all urban housing in South Africa was classified as ―shacks‖ (Population Reference Bureau, 2008). Additionally, of the 11.89 % of South Africa’s population that resides in shacks, 19.94 % of these people are in Gauteng (Statistics South Africa 2007). Informal settlements lie outside of the formal planning process and usually lack or have low levels of basic services such as water and sanitation (Abbott 2002). Overcrowding makes the removal of wastes (garbage collection) difficult and residents end up creating their own waste dumps. Informal settlements are frequently formed in the vicinity of rivers and streams, which serve as water supplies
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River water quality changes in New Zealand over 26 years: response to land use intensity

River water quality changes in New Zealand over 26 years: response to land use intensity

Abstract. Relationships between land use and water quality are complex with interdependencies, feedbacks, and legacy effects. Most river water quality studies have assessed catch- ment land use as areal coverage, but here, we hypothesize and test whether land use intensity – the inputs (fertilizer, livestock) and activities (vegetation removal) of land use – is a better predictor of environmental impact. We use New Zealand (NZ) as a case study because it has had one of the highest rates of agricultural land intensification globally over recent decades. We interpreted water quality state and trends for the 26 years from 1989 to 2014 in the National Rivers Water Quality Network (NRWQN) – consisting of 77 sites on 35 mostly large river systems. To characterize land use intensity, we analyzed spatial and temporal changes in live- stock density and land disturbance (i.e., bare soil resulting from vegetation loss by either grazing or forest harvesting) at the catchment scale, as well as fertilizer inputs at the national scale. Using simple multivariate statistical analyses across the 77 catchments, we found that median visual water clar- ity was best predicted inversely by areal coverage of inten- sively managed pastures. The primary predictor for all four nutrient variables (TN, NO x , TP, DRP), however, was cat-
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Assessment of impact of land use change on the wetland in Makhitha village, Limpopo province, South Africa

Assessment of impact of land use change on the wetland in Makhitha village, Limpopo province, South Africa

Land is a finite resource where all human activities are undertaken. The main purposes of land use are building human settlements, recreation and practising agriculture such as keeping livestock and growing of vegetables and crops. Land use is of major importance to humanity such that several disciplines are focused on land issues (William & Riebsama 1993). Land use change is fundamentally a spatial process, resulting from the collective outcome of a myriad of socio-economic, institutional, biophysical and ecological processes (Wu & Wu 2013). Land use changes driven by human activity have the potential to significantly affect food security and the sustainability of the world agricultural and forest product supply systems (Popp et al. 2014). Land use change is a feature of both rural and urban areas and occurs in both developed and developing countries (Galbraith, Amerasinghe & Huber-Lee 2005; MEAB 2005). Land use change is an essential component, and it is used as an indicator of the development in an area or in a country. Wetlands are gaining recognition because of their unique contribution to aquatic ecosystems and have classified and protected according to the Ramsar Convention of 1971, articles 1.1 and 2.1 (Galbraith et al. 2005). South Africa has been a signatory to the Ramsar Convention and has enacted legislation, such as the National Water Act (Act 36 of 1998) and the National Environmental Management Act (Act 107 of 1998) to protect wetland from further destruction and degradation (Cowan 1995).
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The Spatial and Temporal Variations of Ichythyofauna and Water Quality in the Crocodile River (East), Mpumalanga, South Africa

The Spatial and Temporal Variations of Ichythyofauna and Water Quality in the Crocodile River (East), Mpumalanga, South Africa

The lower reaches of the Crocodile River was found to have poor water quality compared to the upper and the middle reaches. This was also confirmed by the k-dominance curve which indicated that during low flow condi- tion fish communities at sites CR3 and CR4 were dominated by a single species namely Chiloglanis pretoriae while site CR10 was dominated by Barbus viviparus. The presence of Barbus viviparus species at site CR10 in- dicated that the site was poor in water quality as this species is tolerant to such condition. The change in water quality in the lower reaches was associated with agricultural, industrial, mining and sewage treatment effluent in the lower reaches of the river. These activities were also believed to be the source of pollution in the Crocodile River and its tributaries. The use of both biological indicators and water quality in assessing the health of the Crocodile River proved to be valuable. It is suggested that an eco-status approach should be followed when as- sessing the impact of the anthropogenic activities in the rivers as it gives an overview of what is happening in the catchment. The results obtained from this study give an indication of the ecological and water quality status of the Crocodile River and its tributaries. It also contributes to the understanding of the impact of anthropogenic activities such as agricultural, industrial and mining on a river system.
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Effects of land-cover - land-use on water quality within the kuils - Eerste River Catchment

Effects of land-cover - land-use on water quality within the kuils - Eerste River Catchment

Grasslands are important nitrate sources that have been reported previously (Hart et al. 1993; Holloway and Dahlgren, 2001) and attributed to asynchrony within nutrient cycling. Instead of continuous nitrogen feedback among senescing plants, their soils, and new growth (biotic uptake), nitrogen in grasslands is mineralized and accumu- lates in soils during the dry summer months (Hart et al. 1993). With the onset of win- ter rains, water begins to flow through the upper soil horizons, mobilizing the accu- mulated nitrate (Holloway and Dahlgren, 2001) before new growth can uptake nutri- ents. As such, grasslands are inherently leaky systems with respect to nitrate. The pol- lutant with notable variations in concentration is the total suspended solids, which for the two years shows variation as indicated in Figure 7.23. A total of 11 land-cover types showed variations: dense scrub, fynbos, bare ground/impervious surfaces, open area/ barren land, dense/ grassy vineyard, fallow/ open vineyard, arterial roads/ main roads, high density residential (HDR) formal townships, HDR formal suburb, medi- um density residential (MDR) informal Township and industrial areas. The variations are due to the effects of the conversion of agricultural land into urban settlement in- cluding current agricultural activities.
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Historical events and land use changes shaping the Isipingo river catchment, Kwazulu Natal, South Africa

Historical events and land use changes shaping the Isipingo river catchment, Kwazulu Natal, South Africa

Total phosphate and suspended solids levels were found to be exceeding the standards set by the Department of Environmental Affairs at most of the sampling sites monitored by Umgeni Water (Kalicharran and Diab, 1993). According to Ramm (1987), the survey conducted by the Council for Scientific and Industrial Research (CSIR) in August 1985, the dissolved oxygen levels in the Lagoon at the surface and the bottom was approximately 6 ppm which is considered to be about 50% saturation. At the Southern Arm, dissolved oxygen has always been present in surface and bottom water (Begg, 1978; Forbes and Demetriades, 2008). According to Philip (2010), the bottom sediment along the mangrove area (i.e. near the northern arm) consists largely of sludge which leads to the creation of an anoxic zone. The northern arm was ‘virtually devoid of oxygen’ although at times, due to algal blooms, the surface water became super saturated, whilst the bottom water remained anoxic (Begg, 1978; Forbes and Demetriades, 2008). The estuary is characterized by the accumulation of very fine, soft anaerobic material in the mid and upper reaches and the sediment contains high metal concentrations including iron, mercury, lead and zinc (SSI, 2011). There has also been an increase in the frequency of fish kills at the Lagoon area which has been attributed largely to sewage overflows as a result of pump station failures, breaks in the sewer lines and blocked manholes (Philip, 2010). The water quality upstream of the sluice gates is also considered unacceptable (Forbes and Demetriades, 2008).
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Effects of Land Use and Seasonality on the Distribution of Mayflies and Water Quality along Thika River, Kenya.

Effects of Land Use and Seasonality on the Distribution of Mayflies and Water Quality along Thika River, Kenya.

Additionally, Schafer et al. (2012) reported that the use of pesticides had highly increased for two decades, currently the usage continues to rise. Land runoff and direct spraying of chemicals exercised in agricultural and urban areas are essential pathways for introducing pesticides to water systems (Schafer et al., 2012). Moreover, Duchemin & Hogue (2009) observed a direct correlation between the pesticide levels and farm inputs in the watershed, in samples obtained from 27 streams in Alberta. Tran et al. (2010) documented that agricultural fields in Flanders extended to the riparian regions of rivers, and these lead to increased levels of fertilizers and pesticides as a result of surface runoff from the lands. Aura et al. (2010) found that nutrients (phosphorous and nitrogen) concentration varied among the stations and increased downstream along Rivers Kipkaren and Sosiani in the Nzoia basin. Song et al. (2009) observed that most of the agricultural sites in France were characterized by high levels of conductivity, which most likely resulted from high loads of organic and inorganic suspended materials in the increased runoff from the agricultural field.
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Assessing the impact of land use on water and nutrient fluxes in the South-West Mau, Kenya

Assessing the impact of land use on water and nutrient fluxes in the South-West Mau, Kenya

75 loads in rivers. Increased nutrient concentrations as a consequence of fertilization can reduce ecological quality of rivers and lakes and affect aquatic life. The high-resolution data collected in this study shows responses to storm events, the processes behind the different responses and hot moments for NO 3 -N export. This study highlights the need for wider application of high-resolution monitoring to better understand catchment functioning through analysis of hysteresis loops and hot moments. Although the use of in situ instruments has its own challenges, such as security, power supply and maintenance, continuous development of sensor technology and reduction in costs increasingly enables deployment of such sensors, also in remote areas. This is especially relevant in many tropical regions that are vulnerable to land use and climate change. While there is some similarity in general NO 3 -N dynamics between our study catchments and temperate catchments, such as increased NO 3 -N concentrations and yields due to fertilizer application, dilution of NO 3 -N concentrations during rainfall events and the importance of groundwater as source of NO 3 -N, underlying biogeochemical processes, like denitrification and decomposition of organic matter, that strongly depend on climatic factors such as precipitation, soil moisture and temperature, are likely to respond differently in tropical regions, where seasonality is often defined by precipitation rather than temperature differences. Therefore, studies using such high-resolution monitoring systems provide valuable data and information to reduce the current knowledge gap in the understanding of the hydrological functioning of and nutrient fluxes in tropical ecosystems.
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A river health assessment of selected South-Western Cape Rivers : index of habitat integrity, water quality and the influence of surrounding land use

A river health assessment of selected South-Western Cape Rivers : index of habitat integrity, water quality and the influence of surrounding land use

In South Africa water resources are limited (WRC 2001, 2002; RHP 2003, in prep.) and, consequently, South African Stream ecosystems are facing increasing stresses due to over- utilisation of water in an already over-stressed, drought-prone region (Davies and Day 1998). In South Africa rivers provide almost all of the water supply for a rapidly expanding population (Davies and Day 1998) and almost every permanent stream is regulated either by single or multiple impoundments (Davies and Day 1998; Kleynhans 1996). However, the natural water environment is not regarded as a user in competition with other users (e.g. domestic, agricultural, industrial) but rather as a resource base from which water originates and as an entity with its own intrinsic environmental value (Kleynhans 1996). In 1994 the South African Department of Water Affairs and Forestry (DWAF) initiated the National River Health Programme (RHP) as a tool to monitor the ecological state of rivers (Roux et al. 1999; WRC 2001, 2002; RHP 2003, in prep.), the results of which should be incorporated into a water resource management database system (Roux et al. 1999). To determine river health (condition) the RHP applies scientifically derived indices to assess ecological indicators considered to be representative of the wider river ecosystem (Chapter 1). The results are then used to class the river ecosystem in terms of its degree of modification relative to a natural benchmark (undisturbed) condition (Roux et al. 1999; Rowntree et al. 2000). One such index is the Intermediate Index of Habitat Integrity (Kemper 1999).
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Occurrence of PAHs in water samples of the Diep River, South Africa

Occurrence of PAHs in water samples of the Diep River, South Africa

Although Nap, the smallest of the PAHs, is relatively volatile compared to others, it was considerably magnified, reaching 14.28 µg/L at Site DB during summer. This may be linked to high petrogenic emission of lower molecular weight PAHs with increased industrial and vehicular activities, coupled with low or no rainwater dilution during the summer months. The detected levels of Nap exceed the USEPA regulatory threshold limit of 1.10 µg/L for naphthalene in water for the protection of aquatic life, except during autumn and winter at Sites DA/DB and winter at Site DC (US EPA, 2006). Phe and Ant, which differ structurally (isomers), were the two 3-ringed PAHs detected at higher concentrations compared to Acy, Can and Flu. The detected levels reached a maximum of 37.93 µg/L (in autumn) and 23.00 µg/L (in summer) for Phe and Ant, respectively, at Site DB, exceeding the threshold limit of 0.400 µg/L and 0.012 µg/L for phenanthrene and anthracene, respectively (USEPA, 2006). The prevalence of these 3-ringed PAHs at Site DB may be linked to PAH emission from the petrochemical refinery which is proximal to the site. The detected concentrations of other PAHs among the measured 16 in water samples from the Diep River were extremely high relative to the USEPA water quality guideline (USEPA, 2006). The observed levels of some of the measured PAH fractions exceeded the 0.015 to 5.800 µg/L threshold range of the CCME (Canadian Council of Ministers of the Environment) water quality guideline recommended for the protection of aquatic life (CCME, 1999). Hence, water samples of the Diep River may be considered highly polluted with PAHs and capable of impacting aquatic life adversely. In general, suggested probable carcinogenic PAHs (C PAHs), namely, BaA, Chy, BbF, BkF, BaP, IcP and DBA, were prevalent in the Diep River water (see Table A5, Appendix), and contribute up to 72.36% of the total PAHs evaluated. This implies the potential of risk to native and mobile aquatic life as well as an impact on humans who may depend on these water resources. The observed concentration range of the PAHs is consistent with Figure 3. Seasonal variations and annual average levels of the
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Water markets in the Lower Orange River catchment of South Africa

Water markets in the Lower Orange River catchment of South Africa

The buyers of water rights tend to specialize in the production of few crops that are highly profitable such as export grapes. Buyers are often livestock owners. Livestock are seen as a liquid asset, which may be a means of financing water market purchases. The short five-year review period has a negative impact on the purchase of water rights. This could be explained by the fact that the planning horizons for grape producers exceeds five years and requires an assured supply of water for the duration of the crops lifespan. Export grapes and horticultural crops are seen as more profitable alternatives, which require intensive investment in advanced irrigation systems. High quality export grapes require heat and water, with no heavy rainstorms that can damage the grapes. Areas such as Kakamas are more suited to the production of table grapes than other areas such as Boegoeberg and water tends to be purchased by farmers in Kakamas. The water market has facilitated a transfer of water use from relatively lower value crops to relatively higher value crops, and also promoted the use of more advanced irrigation, although this is an indirect effect, since the irrigation type is dependent on the requirements of the crop and strategy of the farmer. From this evidence, it is apparent that the water market meets the objective of efficiency and allows flexibility of water allocations. The transfer of water out of Boegoeberg has no negative employment effects on this area, as the transferred water was not used for irrigation. Sellers are compensated through the selling price of the water and are only selling excess water and not ceasing irrigation.
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Land use practices and their impact on the water quality of the Upper Kuils River (Western Cape Province, South Africa)

Land use practices and their impact on the water quality of the Upper Kuils River (Western Cape Province, South Africa)

40 2.5.2.4 Acidification Acidification of freshwater is a critical problem in many regions of the world. Acid deposition affecting fresh water originates from sulfur dioxide and nitrogen which are released into the atmosphere through burning of fossil fuels (Perry and Vanderklein, 1996). Acidification of natural water is also determined by bedrock (CSIR, 2010), biotic activities (Davies and Day, 1998), and dominant wind and climate patterns that are responsible for the deposition patterns of acidifying elements (Perry and Vanderklein, 1996). Acidification effects are influenced by the timing of acid deposition, the source and rate of acid deposition and buffering capacity of soils and bedrock (Perry and Vanderklein, 1996). Many South Africa fresh water resources are relatively well buffered (CSIR, 2010) and more or less neutral, with pH value around 6 to 8 (Dallas and Day, 2004). However, human activities such as industrial effluents from mine drainage, and acid-rain may decrease the pH value in many South African aquatic ecosystems (CSIR, 2010). Although the South African coal mining industry contributes large revenues for the country (e.g 16% of export revenue in 2003), it presents a great environmental risk from the coal fields. Acid mine drainage (AMD) has major consequences such as ground water, soil quality, and surface water degradations (CSIR, 2010). Acid mine drainage from active and abandoned mines contribute to lowered pH levels , elevated concentration of metal ions and dissolved salt dominated by sulphate (CSIR, 2010; Coetzee, undated).
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Dynamics of Land Cover and Impact on Stream flow in the Modder River Basin of South Africa: Case Study of a Quaternary Catchment

Dynamics of Land Cover and Impact on Stream flow in the Modder River Basin of South Africa: Case Study of a Quaternary Catchment

The contribution of land cover change to streamflow was evaluated by analyzing historical land cover dynamics with reference to streamflow and rainfall patterns. Results suggest that land cover change is one of the major factors influencing streamflow in the C52A catchment. Increase in streamflow coincided with dramatic changes in land cover within the catchment. Management of land use change will be vital for streamflow generation. Future decisions on land use in the catchment will be vital in determining the flow regime and ultimately the water balance in the catchment. Water balance at a catchment level is important since it informs water resource allocation for different user groups including the environment. The increase in streamflow over time suggests that there is increased runoff, usually accompanied by increased rates of erosion and siltation. It can also be discerned from the results that long-term monitoring of land use changes is important for determining trends in hydrology. This information is also important for the development of decision support tools for catchment farmers and managers and to inform policy. In order to ensure sustainable management of the catchment, soil and water conservation measures will be critical within the broader context of integrated water resources management.
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BUFFER ZONE VERSUS WHOLE CATCHMENT APPROACHES TO STUDYING LAND USE IMPACT ON RIVER WATER QUALITY

BUFFER ZONE VERSUS WHOLE CATCHMENT APPROACHES TO STUDYING LAND USE IMPACT ON RIVER WATER QUALITY

The type of vegetation within a buffer strip is also important in determining its effectiveness. Osborne and Kovacic (1993) found that, on an annual basis, forested buffers were able to reduce concentrations of nitrate more than grassed buffers. However, in the same study, grass buffers were found to be more effective in retaining total and dissolved phosphate. Our results show that both field and forested buffer strips play a role in reducing the amount of pollutants, such as chloride, copper and total solids, entering a river. However, the nutrient variability in the rivers appeared to be influenced by predictors other than the landscape, and the effect of forest or field on water quality could not be determined, most likely due to the influence of point source pollution. The average annual chloride flux derived for High- land Creek (750  150 kg/ha/year) was similar to that determined by a study that involved much greater sampling frequencies. Using a sampling frequency of every 15 minutes for two years, Howard and Haynes (1993) determined that the annual chloride loading for Highland Creek was 5036 tonnes for the 1989– 1990 salting season, or 614 kg/ha/year. They found that only about 45% of the chloride applied to the Highland Creek watershed, mainly in the form of road salt, gets flushed out of the catchment in surface waters. The rest remains in the groundwater.
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Impact of land use on river basin water balance: a case study of the Modder River Basin, South Africa

Impact of land use on river basin water balance: a case study of the Modder River Basin, South Africa

Issues and Challenges of the IRWH Technique With a rainwater harvesting technique such as the IRWH technique, where water is not stored in a container for later use in irrigation, the farmer is forced to plant when the best use of the soil water and rainfall could be made, which would be during the rainy season. In the study area the bulk of the rain falls in mid- and late summer, which should be the planting time for suitable crops. Unless enough rain has fallen in early spring, or unless water has been stored in the soil from the autumn rains, planting in September and October in this area is risky because of unreliable and low rainfall during those months. However, this happens in some cases, because of a lack of knowledge and skill of the IRWH technique by some of the villagers. Failure of yields from crops planted at the wrong time would be negative experiences, which could lead to rejection of IRWH as an innovation.
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An evaluation of macroinvertebrate-based biomonitoring and ecotoxicological assessments of deteriorating environmental water quality in the Swartkops River, South Africa

An evaluation of macroinvertebrate-based biomonitoring and ecotoxicological assessments of deteriorating environmental water quality in the Swartkops River, South Africa

24 biological traits proved more responsive to human impacts than the ecological traits, indicating the utility of the TBA in biomonitoring. The development of the species at risk (SPEAR) model, that combines different categories of macroinvertebrate traits to evaluate the effects of pesticides on freshwater ecosystems marked an important milestone in the use of species traits in biomonitoring (Liess and Von der Ohe, 2005). In the SPEAR model, macroinvertebrate taxa were grouped according to their vulnerability to pesticides based on their ecological and biological traits: sensitivity to toxicants, generation time, migration ability, and presence of aquatic stages during time of maximum pesticide application (Liess and Von der Ohe, 2005; Beketov et al., 2009). The SPEAR model proved to be a sensitive stressor-specific tool (Liess and Von der Ohe, 2005; Beketov et al., 2009). Because the SPEAR was based on species traits that are mechanistically related to pesticides, and not based on taxonomic attributes such as composition, richness, diversity and abundance, it is less affected by seasonality, and natural biotic community variations (Beketov et al., 2008a; Beketov et al., 2009). These factors made it applicable across wide spatial scales (Beketov et al., 2008a; Beketov et al., 2009). Liess and Beketov et al. (2011) used a similar approach to investigate traits-based vulnerability of invertebrates’ long-term exposure to low concentrations of the insecticide thiacloprid in outdoor mesocosm experiments. Vulnerability was characterised using two trait sets: sensitivity to pesticide and voltinism. Based on these traits, these authors established four macroinvertebrate groups: i) non-sensitive multivoltine, ii) non-sensitive univoltine, iii) sensitive multivoltine and iv) sensitive univoltine. Their approach detected long-term pesticide effects at a level 1 000 times more sensitive than the convention principal response curve (PRC) approach. These studies illustrated the usefulness of the TBA if developed based on a mechanistic understanding between trait occurrence and stressor(s).
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