Modeling the Impacts of Land Cover Changes on Stream Flow Response in Thiba River Basin in Kenya
Samuel M. Kasuni,
Johnson U. Kitheka
Issue:
Volume 6, Issue 1, February 2017
Pages:
1-13
Received:
10 January 2017
Accepted:
21 January 2017
Published:
10 February 2017
Abstract: Soil and Water Assessment Tool (SWAT) was used to model the impacts of land cover changes on stream flow regime in the Thiba River basin covering a surface area of 1648 km2 in central region of Kenya. The basin is characterized by intensive agricultural activities including the largest rice irrigation scheme in Kenya. A study was undertaken to test the capability of the model in predicting stream flow response under changing land use conditions in a typical tropical river basin. Classified land use maps of 1984, 2004 and 2014 were analyzed to investigate land use changes in the basin. Field based survey, National Irrigation Board (NIB), Kenya Meteorological Department and Water Resources Management Authority (WRMA) provided hydro-meteorological data for the study. The results of the study shows that forest cover in the Thiba River basin has decreased by 18.39 % between 1984 and 2014 while area under rice cultivation increased by 9.38 % in the same period. The SWAT Model results showed that there is a significant relationship between the observed and simulated average monthly stream flows in the Thiba River Basin. The Nash-Sutcliffe Efficiency (NSE) and coefficient of determination (R2) during calibration period (1983-1988) were 0.82 and 0.9, respectively, while for the validation period (1989-1993) they were 0.79 and 0.87, respectively. The average monthly stream flows increased by 6.01 m3/s during the wet season and decreased by 1.92 m3/s during the dry season. The changes in stream flow were attributed to the land cover change and rainfall variability. About 35% of dry season flow and 3% of wet season flow was found to have been directly abstracted from the Thiba River. The study recommends that the basin stakeholders should optimize utilization of abstracted water to avert future catastrophic stream flow fluctuations, possibly flooding during the wet season and low or dry riverbeds during the dry months. The high water demand in the dry months can be met by constructing water storage reservoirs to harvest the high runoff during the wet months. Also, it's important that further research on impact of climate change be conducted to better understand the relationship between catchment hydrology and climate change.
Abstract: Soil and Water Assessment Tool (SWAT) was used to model the impacts of land cover changes on stream flow regime in the Thiba River basin covering a surface area of 1648 km2 in central region of Kenya. The basin is characterized by intensive agricultural activities including the largest rice irrigation scheme in Kenya. A study was undertaken to test...
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Physico – Chemical Water Quality Analyses of Lake Alau, North – Eastern Nigeria
Gwana Adamu Mohammed,
Umaru Buba Wakil,
Halima Mohammed Bala,
Wanas Lalai Ndirmbita
Issue:
Volume 6, Issue 1, February 2017
Pages:
14-22
Received:
1 March 2016
Accepted:
13 March 2016
Published:
4 March 2017
Abstract: This study was conducted on the physico – chemical water quality analyses of Lake Alau, North – eastern Nigeria. Water was sampled biweekly for the period of seven months from five sampling stations. The physico – chemical qualities were determined using the methods described by APHA, (1985) and Boyd (1990). The mean values of the physico – chemical parameters of water qualities analysed are 23.04°C, 56.21 cm, 7.8, 6.41 mg / l, 0.68, 0.034 mg / l, 0.07 mg / l, 39.46 mg / l and 56.28 mg / l for temperature, turbidity, pH, DO, BOD, Nitrite, NH3, alkalinity and total hardness of Lake Alau. The results indicated that, there are no variations between the five stations, except ammonia and nitrate which exhibited significant variations. The water quality parameters were within the range recommended for aquatic life; fish production and domestic use. The physico – chemical parameters were within the observed ranges in unpolluted water bodies and also were found to be within tolerable limit for high yield for aquatic life; fish production and domestic use. It provided vital information on about some of the quality status of Lake Alau, and its suitability for fish production and uses. Any variation, weather seasonal or spatial in physical and chemical characteristic of the Lake has being influence by climatic regime and catchment characteristic, i.e. extent of human activities and water volume fluctuations. Farmers bordering the Lake, dispose both their organic and inorganic wastes in to the Lake directly or indirectly. It is recommended that the relevant stakeholder charged with management of the Lake should carry out a sensitization campaign to educate the people on the danger associated with loading of the Lake with waste (toxic), from washing disinfectant or herbicides spraying machine in the Lake Alau.
Abstract: This study was conducted on the physico – chemical water quality analyses of Lake Alau, North – eastern Nigeria. Water was sampled biweekly for the period of seven months from five sampling stations. The physico – chemical qualities were determined using the methods described by APHA, (1985) and Boyd (1990). The mean values of the physico – chemica...
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