Use of limited hydrological data and mathematical parameters for catchment regionalization: a case study of the Osun Drainage Basin, Nigeria

A protocol is proposed for the regionalization and subdivision of catchments based on hydrometric parameters. Such catchment regionalization may assist the development of appropriate catchment management strategies and policies. As a case study, the trends of variations in daily stage and discharge of seven gauging stations located in the 9,900 km2 Osun Drainage Basin (South West Nigeria) were investigated. Linear regression models for all stations show the expected strong positive association of stage and discharge. The estimated daily changes explain only 1.44% of variations in stage, 0.25% variation in discharge and 99.5% in stage-discharge for station 5, 5.5% variation in stage, 0.7% variation in discharge and 99.7% in stage-discharge at station 25, and 10% variation in stage, 8.9% variation in discharge and 100% in stage-discharge at station 27. For the other studied stations, R2 estimated from daily stage and daily discharge give widely varying patterns. R2 estimated from daily stage and daily discharge is non-significant, but is significant for the daily stage-discharge relationship. The derived daily-stage and daily-discharge equations for the seven stations and their corresponding coefficients of determination can be used to classify the basin into three distinct zones. These are Zone I (coefficient of determination within the range of 0-6% for the daily-stage and daily-discharge), Zone II (coefficient of determination within the range of 7-10.5% for the daily-stage and daily-discharge), and Zone III (coefficient of determination within the range of 11-22% for the daily-stage and daily-discharge). The exponents of the stage-discharge equation can also be used for spatial classification. Zone A exponent is in the range of 1.3-1.7, Zone B exponent is in the range 2.2-2.3 and Zone C exponent is in the range 4.0-4.7. These can be combined to produce three hydrometric regions. It is proposed this regionalization protocol could be used as an initial step in dividing complex catchment systems into more homogeneous subunits, to assist subsequent catchment management and planning. The hydrometric regionalization protocol is now being evaluated on the Osun and other drainage basins in Nigeria.Keyword: Derivation, Gauged and Ungauged Rivers, Drainage Basin, Power Equation

Use of farmers' indicators to evaluate the sustainability of cropping systems on sloping land in Yunnan Province, China.

Diversity in the biophysical and socio-economic attributes of agricultural systems makes them uniquely niche based. Farmers are expert in local biophysical and socio-economic situations and can contribute in developing pragmatic indicators of agro-environmental development. During evaluation of an agricultural research project in Yunnan, China, local farmers were capable of evaluating the effects of modified technologies on existing cropping systems and discussed their attitudes to the interventions using their own indicators. Farmers' response can be grouped into seven major aspects: i) effects on income, ii) effects on production resources, iii) effects on crop management, iv) existing local knowledge about the technology, v) availability of inputs, vi) access to information, and vii) socio-economic conditions of farming households. Farmers concluded that environmental conditions in the experimental catchment in comparison to an adjacent untreated catchment were better in terms of soil and water losses, vegetation cover and natural resources, infrastructures and catchment management, use of environmentally-friendly technologies, and crop productivity. Success in soil and water conservation programmes depends on the efforts of the farmers and other local users and their greater involvement helps to identify more pragmatic indicators. Furthermore, it increases ownership of the programme, enhances interactions with the project scientists, increases farmers' awareness of agro-environmental problems and their possible consequences. These development will enable scientists to develop better targeted interventions and increase the likelihood of adoption of tested technologies by local communities. The use of paired adjacent catchments improved evaluation activities and is proposed as good practice for future catchment improvement programmes

Impacts of rising temperature, carbon dioxide concentration and sea level on wheat production in North Nile delta

Climate change poses a serious threat to arid and low elevation coastal zones. Kafrelsheikh governorate, as a large agricultural and coastal region on the Egyptian North Nile Delta, is one of the most vulnerable areas to higher temperature and global sea level rise. Two DSSAT wheat models (CERES and N-Wheat) were calibrated using a local cultivar (Misr3) grown under irrigated conditions in Egypt. Experimental data of two successive growing seasons during 2014/2015 and 2015/2016 were used for calibration using different treatments of irrigation, planting dates and fertilization. Both models simulated the phenology and wheat yield well, with root mean square deviation of b10%, and d-index N 0.80. Climate change sensitivity analysis showed that rising temperature by 1 °C to 4 °C decreased wheat yield by 17.6%. However, elevated atmospheric CO2 concentrations increased yield and could overtake some of the negative temperature responses. Sea level rise by 2.0 m will reduce the extent of agricultural land on the North Nile Delta of Egypt by ~60% creating an additional challenge to wheat production in this region.Agricultural Research Center, Egyp

An investigation of rainfall, runoff and erosion on fallow arable soils in East Shropshire

SIGLEAvailable from British Library Lending Division - LD:D57671/85 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Desert reclamation using Yellow River irrigation water in Ningxia, China

The effects of silt-laden Yellow River irrigation water on the properties of reclaimed dune sands were investigated at the Shapotou Research Station in Ningxia Autonomous Region, China. The practice resulted in distinct and rapid improvements in the physical and chemical properties of reclaimed desert soils. Irrigation led to the development of sandy loam topsoils, with up to 39 cm accumulating over 25 years of treatment. These topsoils had improved structure, greater soil organic matter contents and smaller bulk densities than buried desert sands. Geochemical analyses suggested river silt and sheep manure were making distinctive contributions to the improved soil fertility, with older topsoils having progressively greater concentrations of Ca, Mg, K, P, S, Fe, Mn and Zn. Soil Cr concentrations are increasing and it seems appropriate that changes in heavy metal concentrations in irrigated soils are monitored