The Mara River is the lifeline of the transboundary Mara basin across Kenya and Tanzania. The basin is considered one of the more serene subcatchments of the Lake Victoria Basin and ultimately the Nile Basin, and traverses the famous Maasai Mara and Serengeti National Parks. The basin also contains forests, large-scale farms, smallholder farms, pastoral grazing lands, as well as hunter gatherers and fishers. There is growing concern, however, regarding land degradation in the basin, particularly deforestation in the headwaters, that is affecting the natural resource base and the river flows. Accurate scientific data are required to advise policy, and to plan appropriate mitigation measures. This study utilizes remote sensing and geographical information system (GIS) tools, and hydrological and ground-truth studies to determine the magnitude of the land-use/cover changes in the Mara River Basin, and the effects of these changes on the river flows over the last 30 years. The study results indicate that land-use/cover changes have occurred. In 1973, for example, rangelands (savannah, grasslands and shrublands) covered 10 989 km 2 (79%) of the total basin area. The rangelands had been reduced to 7245 km 2 (52%) by 2000, however, while the forest areas were reduced by 32% over the same period. These changes have been attributed to the encroachment of agriculture, which has more than doubled (203%) its land area over the same period. The hydrology of the Mara River also has changed, with sharp increases in flood peak flows by 7%, and an earlier occurrence of these peaks by 4 days between 1973 and 2000. There is evidence of increased soil erosion in the upper catchments, with silt build-up in the downstream floodplains. This has caused the Mara wetland to expand by 387%, adversely affecting riparian agriculture. There is need for urgent action to stem the land degradation of the Mara River Basin, including planning and implementing appropriate mitigation measures.

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There are various avenues for intensifying agricultural production, the most common being increased use of fertilizers, supplemental irrigation of crops, and adoption of high-yielding varieties. These options are rather widely known to farmers around the world, but they have not been widely adopted by smallholders in subSaharan Africa. The low adoption rate is related to complex technical and socio-economic issues, such as poor extension services, lack of capital, failure to mobilize the requisite water, or simply, poverty. The System of Rice Intensification (SRI) is in a special category of innovation in that, farmers stand to gain multiple benefits from its use, including the possibility of increasing rice yields substantially, saving water, and getting better grain quality, using differently the assets that they already have. A major impediment for the adoption of SRI in Africa has been lack of knowledge about this intervention, especially for farmers already practicing irrigated agriculture. Farmers generally have good business sense and will adopt technologies or practices once the benefits are proven and the risks are seen as minor. SRI should be attractive for these reasons, but there are various issues to be resolved before large numbers of farmers can adopt the method. This article reports on the steps taken and the technical and socio-economic issues addressed in efforts to introduce SRI and promote it in Kenya, specifically in the Mwea Irrigation Scheme. A diverse set of individuals and institutions in Kenya together embarked on the evaluation and dissemination of SRI methods in this East African country beginning in July 2009. If the new methods can perform in Kenya as in other countries, this will bring much benefit to rice farmers and rice consumers in the region. SRI is coming to Kenya relatively late, as it was the thirty-ninth country from which favorable SRI results have been reported. This means that Kenyans can learn from others' experience and evaluations, and there is also now more of a supportive institutional framework. The initial results from on-farm SRI trials have been positive, although not conclusive. They have given impetus to Kenyan farmers and institutions to collaborate within a multi-sectoral, multilevel coalition that has provided an informal, multi-faceted platform for the evaluation, adaptation and dissemination of SRI practices. The initiative in Kenya is now gaining more formal status and more resources. This experience is presented to show the kinds of things that have been and can be done to utilize the SRI opportunity for raising land, labor, and water productivity in the rice sector.

Sand dams are one of the most successful rainwater harvesting methods, adopted in most of arid and semi-arid lands (ASALs) of Kenya to secure domestic water supply and micro-irrigation. Their ability to maintain acceptable water quality, under extreme climatic conditions of recurrent drought and floods, is therefore of paramount public health concern as various pollutants find easily their way into them. This study assessed the suitability of sand-dam water abstracted via scoop holes (SCHs) and shallow wells (SHWs) in Kitui-West, South-Eastern Kenya. Water quality compliance checks were performed using the specifications of Kenya Bureau of Standards (KEBS) for natural potable water and World Health Organization's (WHO) drinking-water quality guidelines wherever applicable. A total of 48 water samples comprising SCHs (N=33) and SHWs (N=15) were collected during the dry period (February 8 and 28, 2018) and the wet season (March 23, April 20 and May 19, 2018) in three sand dams using well-cleaned plastic bottles, transported in cooler boxes to the laboratory for storage and analysis. They were analyzed for pH, temperature, total dissolved solids (TDS), total hardness (TH), biochemical oxygen demand (BOD), trace metals (Cu, Fe, Mn, Zn, and Cr), Escherichia coli (E. coli) and total coliforms (TCs). Results showed that majority of assessed physicochemical parameters and trace metals complied with KEBS limits at the rates of more than 90% except turbidity, Cu and Fe that complied with low overall scores; 44, 56 and 35% respectively. These three parameters behaved differently in both abstraction methods as their mean values (compliance rates) exceeded KEBS limits in SCHs, that is, 297 NTU (18%), 1.7 mg/L (48%) and 2.22 mg/L (9%) and were below limits in SHWs, that is, 3.1 NTU (100%), 0.89 mg/L (73%) and 0.21 mg/L (87%) respectively. E.coli compliance levels were 48% in SCHs and 87% in SHWs with maximum counts as 300 CFU/100 ml, while TCs were detected at high rates of 94 and 47% respectively with maximum counts as 2,500 CFU/100 ml. Therefore, these results demonstrated that water extracted via SCHs is more unsafe than water from SHWs but both provide water that is microbiologically unfit for direct human consumption. Shallow-well water was found to be physicochemically fit and only requires disinfection while scooped water needs first to be purified with homemade water filters and then chlorinated with available disinfection by-products (DBPs) to increase its potability. Continuous monitoring of sand-dam water quality is recommended so that the public awareness should be raised on time when new contaminants emerge or exiting ones become intense so as to avoid possible health risks that can result from unnoticed long-term exposure.

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