Impacts of agricultural intensification through upscaling of suitable rainwater harvesting technologies in the upper Ewaso Ng'iro North basin, Kenya

Abstract

Changes in land cover and land use can lead to significant impacts to hydrology by affecting the amount of runoff, soil moisture and groundwater recharge over a range of temporal and spatial scales. However, hydrologic effects of these changes are still an unknown at watershed scale. Moreover, predicting the effects of land cover/use and climate change on hydrological cycle has remained a major challenge. This is because of the complexity and uncertainty of future climate changes making it difficult to predict the consequences. It is against this backdrop that, for sustainable water resources management, assessment of the impacts of land cover/use change on hydrological regime at all scales becomes critical. During this study, we applied the SWAT model to assess the impacts of area hydrology between baseline and alternative scenario (upscaling of rainwater harvesting technologies). Specifically, our overall objective was to quantitatively evaluate the effects of land use changes on watershed hydrology in the upper Ewaso Ng'iro North basin in Kenya. This was achieved by estimating hydrological responses under historical land use scenarios obtained from the multi-temporal satellite imageries of 1987, 1995 and 2003. The model performance was found to be relatively good (Nash and Sutcliffe efficient of 70%). Stream flow analysis was carried out for different parts of the basin to understand its hydrological responses, especially, the behavior of base flow. The results show a decrease in base flow during 1987–2003 period with decreasing forest, bush and grass covers, which can be attributed to poor natural vegetation emanating mainly from overgrazing and deforestation for agricultural activities. In conclusion, the study clearly shows that, assessment of hydrologic effects of land use changes is critical for a sustainable water resources planning and management of the basin

The Impacts of Water Demand and Its Implications for Future Surface Water Resource Management: The Case of Tanzania’s Wami Ruvu Basin (WRB)

“…Water resources are inextricably linked with climate, and the prospect of global climate change has serious implications for future water resources and regional development [1,2,[30][31][32]. The large variation in the spatial and temporal distribution of water resources in the Sokoto Rima River basin, the Didessa sub-basin, the Niger River basin, etc., will make the consequences of water scarcity even more severe unless DSM strategies are implemented which prove to be effective in minimizing the future growth in water demand and basin surface runoff.…”

A water footprint approach to guide water resource management in data-scarce regions: A case study for the Upper Ewaso Ng’iro Basin, Mount Kenya

“…According to Mutiga et al (2011), grasslands occupied 18% of the basin area in 2003 (down from 20.5% in 1987), while according to CETRAD (2014) grassland covered 43%. Mutiga et al (2011) also included a 'bareland' land use category (covering 24.1%), however, which was not considered by CETRAD (2014). We, therefore, used only the grassland category, estimated to cover 43% of the area.…”

“…According to Mutiga et al (2011), surface waters cover 1% of the basin or 15 200 ha. Ngigi et al (2008) reported that water bodies cover 0.04% of the Naro Moru sub-basin.…”

“…The highland-lowland Upper Ewaso Ng'iro Basin, Kenya, is a good example where both population growth and agricultural intensification has increased water scarcity, evident from cases of river flow no longer reaching the basin's outlet for stretches of time during the year. It has been reported that flows in the basin have decreased by 30%, with an estimated 60-95% of available water extracted from rivers during the dry season; up to 90% of these abstractions are illegal (Kiteme and Gikonyo, 2002;Mutiga et al, 2011;Ngigi et al, 2008;Notter et al, 2007). For the Naro Moru River, Aeschbacher et al (2005) estimated that 97% of abstracted water was used for irrigation on 9% of the catchment land area, constituting 80-100% of the dry season flow.…”

Benefits of Riverine Water Discharge into the Lorian Swamp, Kenya

“…Various authors have studied the effects of abstractions upstream on the discharge of the Ewaso Ng'iro River, with some using models to predict the effects of these abstractions on downstream discharge [12]. While such models are useful to gain understanding in systems behavior, we decided to present in this paper the reported permitted abstractions and estimates of the demand for water to give an impression of the magnitude of the abstractions in the upper part of the catchment.…”