Flood events cause considerable losses and damages in many areas of Iran each year. Evaluation of flood control projects to improve the future design of the projects is an efficient and effective way to reduce the consequences of flood... more
Flood events cause considerable losses and damages in many areas of Iran each year. Evaluation of flood control projects to improve the future design of the projects is an efficient and effective way to reduce the consequences of flood events. The focus of this study is on the evaluation of the Jafar-Abad structural flood control project to examine the hydrologic performance of the check dams constructed in the watershed. Also the hydrologic and economic effects of six potential structural management scenarios were predicted in order to inform and assist watershed managers in the design of flood control projects. The Jafar-Abad Watershed (109 Km2) is located in the Golestan Province, north of Iran. The six structural management scenarios were developed considering the changes in location, height and numbers of check dams constructed along the water courses in the watershed. The calibrated HEC-HMS model was used to simulate rainfall-runoff relationships in sub-watersheds. Using the flow data recorded at a river gauge station located on the outlet of the watershed, paired t-test was performed to compare hydrologic conditions before and after the construction of 58 check dams already constructed in the watershed. For each scenario, flood hydrographs for 2 to 100 year return periods were calculated. To predict the potential impacts of implementing the management scenarios on flood characteristics, indices such as peak flow, time to peak and base time of hydrographs and construction costs were chosen and quantified for each management scenario at the different return periods. The indices then were standardised using the maximum standardisation method. To weight the indices, expert knowledge was elicitated using the Delphi process. The most appropriate management scenarios from both hydrologic and hydro-economic perspectives were assigned using a Multi Criteria Decision Making (MCDM) approach for the various return periods. Sensitivity analysis with regard to different weights of the indices was conducted. The statistical t-test indicates that the existing check dams in the watershed had no significant hydrologic impacts. The MCDM results show that scenario 7 (increasing the number of check dams, from 58 to 69) would be the most appropriate management scenario from the hydrological perspective. However, most appropriate management scenarios from both hydrologic and hydro-economic perspectives are scenario 1 (no action) and scenario 5 (with only 15 check dams constructed on an upstream sub-watershed), respectively. This kind of evaluation and prediction assists the designers of flood control projects to choose the most preferred management option/s considering the hydrologic as well as economic considerations.
RUVIVAL Publication Series is a compilation of literature reviews on topics concerned with the revitalisation of rural areas. RUVIVAL Publication Series is part of the e-learning project RUVIVAL and each of the three contributions in this... more
RUVIVAL Publication Series is a compilation of literature reviews on topics concerned with the revitalisation of rural areas. RUVIVAL Publication Series is part of the e-learning project RUVIVAL and each of the three contributions in this publication is connected to further interactive multimedia material, which can be reached under www.ruvival.de. The first literature review is concerned with urine utilisation as a fertiliser in agriculture. Urine contains four important nutrients for plant growth: nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) and its use as fertiliser can not only recover these nutrients, but also reduce the use of chemical fertilisers and freshwater, as well as minimise the wastewater and excreta contamination of surface and open waters. However, if not managed properly, the risk of pathogen transmission, soil salinisation and pharmaceutical contamination, as well as strong and offensive odour, can cause significant health problems and discomfort. T...
Agroforestry is the inclusion of trees or other woody perennial plants into agricultural systems, including crop and livestock production. It can also be seen as a combination of agriculture and forestry. While conventional large scale... more
Agroforestry is the inclusion of trees or other woody perennial plants into agricultural systems, including crop and livestock production. It can also be seen as a combination of agriculture and forestry. While conventional large scale agriculture is mainly concerned with maximising short term yields, agroforestry has the objective of emulating natural ecosystems in order to realise a number of ecosystem services. Those include the protection of soil against erosion and water-logging, minimising evaporation of water from soil and plants by decreasing wind speed, water protection through deeper and more extensive root systems and increased biodiversity. Long term stability and productivity of agroforestry systems surpasses those of conventional monocultures or pasturelands, as they tend to be more resilient, but the establishment of trees on farmland comes with certain challenges. Until the trees start to pay off, several years or even decades might pass. The right combination of tre...
Agroforestry is the inclusion of trees or other woody perennial plants into agricultural systems, including crop and livestock production. It can also be seen as a combination of agriculture and forestry. While conventional large scale... more
Agroforestry is the inclusion of trees or other woody perennial plants into agricultural systems, including crop and livestock production. It can also be seen as a combination of agriculture and forestry. While conventional large scale agriculture is mainly concerned with maximising short term yields, agroforestry has the objective of emulating natural ecosystems in order to realise a number of ecosystem services. Those include the protection of soil against erosion and water-logging, minimising evaporation of water from soil and plants by decreasing wind speed, water protection through deeper and more extensive root systems and increased biodiversity. Long term stability and productivity of agroforestry systems surpasses those of conventional monocultures or pasturelands, as they tend to be more resilient, but the establishment of trees on farmland comes with certain challenges. Until the trees start to pay off, several years or even decades might pass. The right combination of tre...
Agroforestry is the inclusion of trees or other woody perennial plants into agricultural systems, including crop and livestock production. It can also be seen as a combination of agriculture and forestry. While conventional large scale... more
Agroforestry is the inclusion of trees or other woody perennial plants into agricultural systems, including crop and livestock production. It can also be seen as a combination of agriculture and forestry. While conventional large scale agriculture is mainly concerned with maximising short term yields, agroforestry has the objective of emulating natural ecosystems in order to realise a number of ecosystem services. Those include the protection of soil against erosion and water-logging, minimising evaporation of water from soil and plants by decreasing wind speed, water protection through deeper and more extensive root systems and increased biodiversity. Long term stability and productivity of agroforestry systems surpasses those of conventional monocultures or pasturelands, as they tend to be more resilient, but the establishment of trees on farmland comes with certain challenges. Until the trees start to pay off, several years or even decades might pass. The right combination of tre...
Small village farmers on Mauritius and Rodrigues Islands have been forced by water scarcity to reduce the amount of land they can cultivate by 2/3 In some instances they have been forced to purchase expensive water from retailers bringing... more
Small village farmers on Mauritius and Rodrigues Islands have been forced by water scarcity to reduce the amount of land they can cultivate by 2/3 In some instances they have been forced to purchase expensive water from retailers bringing it around on carts. This has reduced their farm income and pushes them closer to poverty. This is on an island that receives over 373 mm of rain even during drought. This problem can be solved quickly and inexpensively using properly located check dams. While we use Rodrigues island as a example the solution can be applied in a much broader context across water scarcity regions in Africia, Asia and the middle East.
Soil erosion in southeast Spain is a complex process due to strong interactions between biophysical and human components. Significant progress has been achieved in the understanding of soil hydrological behavior, despite the fact that... more
Soil erosion in southeast Spain is a complex process due to strong interactions between biophysical and human components. Significant progress has been achieved in the understanding of soil hydrological behavior, despite the fact that most investigations were focused on the experimental plot scale. Although experimental plots allow exploring the effect of multiple biophysical and anthropogenic factors, they provide limited insights in the combined effect of all factors acting together at the landscape scale. In this study, area-specific sediment yields (SSY) have been estimated based on the volume of sediment trapped behind 36 check dams in the southeast of Spain. Low SSY-values were reported (mean = 1.40 t ha−1 year−1: median = 0.61 t ha−1 year−1). SSY variability could be explained for 67% by catchment characteristics such as drainage area, soil characteristics, land cover, average catchment slope, and annual rainfall. The low SSY values are probably caused by the agricultural abandonment that occurred over the past decades and allowed the recovery of natural vegetation. Furthermore, our results suggest that the soils have eroded in the past to such an extent that nowadays not much sediment is detached by overland flow due to residual enrichment of clay and stones. Also, sediment is to a large extent trapped locally in the catchment, as indicated by the negative relationship between SSY and catchment area.► Area-specific sediment yields have been estimated for 36 check dams (SE Spain). ► SSY are unexpectedly low (mean = 1.40 t ha− 1 year− 1: median = 0.61 t ha− 1 year− 1). ► This can be the result of the low bedrock erodibility and the shallow soil profiles. ► Sediment detachment is also reduced due to residual enrichment of clay and stones. ► Vegetation cover and agricultural activities control as well the SSY variability.
