Review of the Role of Remote Sensing Technology in Water Resources Management

The human race through the ages has striven to locate and develop water resources. One of the main challenges in sustainable management and utilization of both surface and ground water resource is obtaining accurate hydrological, meteorological and topographic information which are essential inputs in identification of opportunities and treats. Remote monitoring, via satellite assets and distributed in situ sensors, may help meet many of the challenges of information asymmetry and data gaps in developing countries. Total suspended soils (sediment concentration), oil pollution, eutrophication, municipal and industrial discharge and other water quality deteriorating factors can be observed through using remote sensing technologies. Obtaining accurate precipitation data for hydrological simulations and predictions is a challenging task in developing countries and regions with complex terrains that have no or sparse rain gauge networks. Recently, the rapid development of satellite remote sensing technology has provided hydrologists an unprecedented opportunity to better estimate precipitation for hydrological applications. Remotely sensed data acquired by operational satellites are more and more widely used for the identification, monitoring and delineation of lake mapping at regional or global scales. Currently different remote sensing satellites like: AQUA/TERA (MODIS), QuickBird , SPOT 1-5, IKONOS 1-2, LANDSAT 7. NOAA-GEOS, NOAA-POES and others are being used for obtaining the information about floods inundation areas and flood damage assessment. Even though ground water potential can be identified by different methods, remote sensing technique provides an advantage of having access to large coverage, even in inaccessible areas

Evaluating the Effect of Historical Climate Change on Extreme Stream Flow Cases of Gumara Watershed, Upper Blue Nile Basin, Ethiopia

Climate and land cover change are very important issues in terms of global context and their responses to environmental and socio-economic drivers. The dynamic of these two factors is currently affecting the environment in unbalanced way including watershed hydrology. The change of observed steam flow is the effect of the combined change of climate and land use land cover of the catchment. In this paper the impact of climate change on stream flow specifically on extreme flow events were evaluated through application of Soil and Water Assessment Tool (SWAT) model in Gumara watershed, Upper Blue Nile basin Ethiopia. The trend of regional climate, like temperature, rainfall and evapotranspiration of the past 40 years in the study area were tested and then the extent of changes has also been evaluated in terms of monthly bases by using two decadal time periods. The period between1973-1982 was taken as baseline and 2004-2013 was used as change study. The efficiency of the model was determined by Nash-Sutcliffe (NS) and Relative Volume error (RVe) and their values were 0.66 and 0.72% for calibration and 0.64 and 1.23% for validation respectively. Both the high and low flows of the catchment have been taken from the simulated stream flow. The high flow has been identified using Annual Maximum (AM) method and the low flow was also identified by using Seven Day Sustained (SDS) minimum annual flow of the river. The impact of climate change was more significant on high stream flow than low flow of the catchment. Due to climate change, when the high flow was increasing by 17.08%, the low flow was decreasing by 6%. The overall results of the study indicated that Climate change is more responsible for stream flow during wet season than dry season. Keywords: Climate, High flow, Low Flow, SWAT, Gumara, Blue Nile

Indigenous agricultural knowledge: A neglected human based resource for sustainable crop protection and production

Indigenous knowledge, developed over generations and owned by communities or individuals within a community, offers alternative strategies and perspectives on resource management and use. However, as emphasized in the contemporary agricultural history of Ethiopia, the most effective indigenous agricultural knowledge has not been well documented and some of them are replaced by modern techniques. This study was therefore conducted to assess and document community-based techniques to control pests and diseases and the practical implications of indigenous farming techniques. A focus group discussion, key informant interviews and semistructured questionnaires were conducted with 150 farmers. The result showed that a substan tial number (92%) of the farming community uses indigenous based plant protection measures. Indigenous farmers (92%) splash liquids made of cow urine to control the adverse effect of fungi. Farmers are also using different seed selection methods for next season planting. About 29% of the farmers do single head-based seed selection prior to mass harvesting, 34% are collected as “Qerm” and 45% select their seeds during threshing. Indigenous farming knowledge varies with the natural feature of the growing location and cropping system, including the rainfall pattern, soil fertility status, crop, and weed type. The observed positive effect of indigenous agricultural practices on crop production substantiates the need to include these essential approaches in the cultivation system along with the modern agronomic techniques. This might reduce the dependency on expensive and pollutant agricultural inputs. However, sociodemographic factors such as educational level, marital status and farming experience have been found as a determinant factor that influences utilization of indigenous farming knowledge. It can be therefore inferred that documenting indigenous knowledge and proving its applicability scientifically could contribute to organically oriented agricultural production and consequently reduce agriculture’s contribution to environmental pollution

The Dynamics of Hydrological Extremes under the Highest Emission Climate Change Scenario in the Headwater Catchments of the Upper Blue Nile Basin, Ethiopia

Climate change and its impact on surface runoff in the upper Blue Nile basin and sub-basins have been widely studied in future climate projections. However, the impact on extreme flow events of rivers is barely investigated discretely. In this paper, the change in temperature and rainfall under the Representative Concentration Pathway (RCP) highest emission scenario (RCP 8.5) and its impact on the high flow and low flow simulated by the Soil and Water Assessment Tool (SWAT 2012) in major watersheds of the Lake Tana Basin has been evaluated by comparing the baseline period (1971–2000) with the 2020s (2011–2040), 2050s (2041–2070), and 2080s (2071–2100). The high flows of watersheds were selected by the Annual Maximum Series (AMS) model, whereas the low-flow watersheds were selected by the 7-day sustained mean annual minimum flow method. The result showed that the highest change in maximum temperature ranged from 2.93 °C to 5.17 °C in monthly time scales in the 2080s. The increment in minimum temperature is also more prominent in the 2080s and it is expected to rise by 4.75 °C. Inter-annual variability of the change in rainfall has shown increasing and decreasing patterns. The highest increments are expected by 22.37%, 25.58%, and 29.75% in the 2020s, 2050s, and 2080s, respectively, whereas the projected highest decrease in rainfall dictates the decrease of 6.42%, 7.11%, and 9.26% in 2020s, 2050s, and 2080s, respectively. Due to changes in temperature and rainfall, the low flow is likely to decrease by 8.39%, 8.33%, 6.21%, and 5.02% in Ribb, Gumara, Megech, and Gilgel Abay watersheds, respectively, whereas the high flow of Gilgel Abay, Megech, Gumara, and Ribb watersheds are expected to increase by 13.94%, 12.16%, 10.90%, and 10.24%, respectively, every 30 years