Impacts of land use and land cover change on surface runoff, discharge and low flows: evidence from East Africa

Region: East Africa. Focus: A review of catchment studies (n=37) conducted in East Africa evaluating the impacts of Land Use and Land Cover Changes (LULCC) on discharge, surface runoff, and low flows. New hydrological insights: Forest cover loss is accompanied by increased stream discharges and surface runoff. No significant difference in stream discharge is observed between bamboo and pine plantation catchments, and between cultivated and tea plantation catchments. Trend analyses show that despite forest cover loss, 63% of the watersheds show non-significant changes in annual discharges while 31% show increasing trends. Half of the watersheds show non-significant trends in wet season flows and low flows while 35% reveal decreasing trends in low flows. Modeling studies estimate that forest cover loss increases annual discharges and surface runoff by 16 ± 5.5% and 45 ± 14%, respectively. Peak flows increased by a mean of 10 ± 2.8% while low flows decreased by a mean of 7 ± 5.3%. Increased forest cover decreases annual discharges and surface runoff by 13 ± 1.9% and 25 ± 5%, respectively. Weak correlations between forest cover and runoff (r=0.42, p < 0.05), mean discharge (r=0.63, p < 0.05) and peak discharge (r=0.67, p < 0.05) indicate that forest cover alone is not an accurate predictor of hydrological fluxes in East African catchments. The variability in these results supports the need for long-term field monitoring to better understand catchment responses and to improve the calibration of currently used simulation models

Aufbau einer Photovoltaikanlage an der Grund- und Hauptschule Lorup Abschlussbericht

The photovoltaic system will give the pupils practical information on the interdependence between insolation and power yields in their physics and technology lessons. Observations will be continued during the next few years in order to follow up the success of the project.In Schulen fehlen geeignete Demonstrationsanlagen zur paedagogischen Vermittlung regenerativer Umwelttechnik. Somit beschraenkt sich die Darstellung und Vermittlung von innovativer Technik auf rein kognitive Wissensvermittlung. Ziel ist es mit einer Photovoltaikanlage praxisorientierte Informationsgewinnung und -weitergabe zu beguenstigen. Mit dem Aufbau einer Photovoltaikanlage soll auf Jahre hinaus den Schuelern im Physik- und Technikunterricht die Moeglichkeit gegeben werden, neben den in Lorup oder der naeheren Umgebung bereits zu besichtigenden alternativen Energiequellen (Windmuehlen, Holzhackschnitzelheizwerk, Biogasanlage) eine weitere konkret handelnd zu erleben. Durch den Aufbau der Photovoltaikanlage wurde den Schuelern die Moeglichkeit gegeben, konkret handelnd das Zusammenspiel zwischen Sonneneinstrahlung und erzeugter Energiemenge zu begreifen. Durch eigene Anschauung gelingt eine staendige Information ueber diese im Ort Lorup noch sehr alternative Energiegewinnung. Die Arbeit in den naechsten Schuljahren wird zeigen, inwieweit der eingeschlagene Weg Fruechte traegt. (orig.)SIGLEAvailable from TIB Hannover: F02B1709 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDeutsche Bundesstiftung Umwelt, Osnabrueck (Germany)DEGerman

Exploring the relationship between hydroclimatic stationarity and rainfall-runoff model parameter stability : a case study in West Africa

International audienceForecasting the hydrological impacts of climatic and anthropic changes assumes that the evolution of model parameters under changing conditions can be predicted. Hence it is necessary to study the relationship between hydroclimatic variability and model parameter values. In this paper, we explore this issue by implementing a daily lumped hydrological model (GR4J, Perrin et al. (2003)) on the Upper Ouémé watershed (10,050 km2, Benin). West Africa was subjected to changing climatic and hydrological conditions during the second half of the last century, and changes in the water balance can be evidenced on this watershed. Contrasted periods are extracted from the available 1954–2002 data set, so that hydrological and pluviometric extreme periods can be defined. First, the magnitude of changes in model parameter values under changing conditions are analyzed, using a resampling method (first approach) and within an equifinality context (second approach). It is shown that significant changes in the rainfall-runoff relationship do not induce significant changes in the model's parameter values. A third original approach analyzes the signature of hydroclimatic variability in model performance. Hence a test is defined that uses interannual model efficiency variances to measure performance homogeneity and a resampling test to statistically characterize the calculated results. This test demonstrates the hydrological relevance of the calibrated parameter sets because the more stationary the rainfall-runoff relationship, the more homogeneous the model's performance