Abstract: The province of Punjab is the main food basket of India. In recent years, many regions of Punjab are facing acute waterlogging problems and increased secondary salinity, which have negative impacts on food security of the nation. In particular, these problems are more pronounced in the Muktsar district of Punjab. The observed groundwater levels trend between 2005 and 2011 implies that groundwater levels are coming towards the land surface at the rate of 0.5 m/year in Lambi and Malout blocks. In this study, a groundwater flow model was constructed using MODFLOW to understand the groundwater table dynamics and to test the groundwater evaporation ponds to draw down the groundwater levels in the waterlogging areas of Muktsar district. The predicted flow model results indicate that groundwater levels could be depleted at the rate of 0.3 m/year between 2012 and 2018 after the construction of Groundwater Evaporation Ponds (GEP). In addition, the constructed ponds can be used for aquaculture that generates additional income. The proposed GEP method may be a promising tool and suitable for the reduction of waterlogging in any region if there is no proper surface drainage, and also for enhancement of agricultural production that improves the social and economic status of the farming community.
Abstract: Papua New Guinea is blessed with a plethora of enviable natural resources, but at the same time it is also cursed by quite a few natural disasters like volcanic eruptions, earthquakes, landslide, floods, droughts etc. Floods happen to be a natural process of maintaining the health of the rivers and depth of its thalweg; it saves the river from becoming morbid while toning up the fertility of the riverine landscape. At the same time, from human perspective, all these ecological goodies are nullified when flood is construed overwhelmingly as one of the most devastating events in respect to social and economic consequences. The present investigation was tailored to assess the use of multi-criteria decision approach (MCDA) in inland flood risk analysis. Categorization of possible flood risk zones was accomplished using geospatial data sets, like elevation, slope, distance to river, and land use/land cover, which were derived from digital elevation model (DEM) and satellite image, respectively. A pilot study area was selected in the lower part of Markham River in Morobe Province, Papua New Guinea. The study area is bounded by 146°31′ to 146°58′ east and 6°33′ to 6°46′ south; covers an area of 758.30 km2. The validation of a flood hazard risk map was carried out using past flood records in the study area. This result suggests that MCDA within GIS techniques is very useful in accurate and reliable flood risk analysis and mapping. This approach is convenient for the assessment of flood in any region, specifically in no-data regions, and can be useful for researchers and planners in flood mitigation strategies.
Abstract: Large parts of the northern hemisphere are covered by snow and seasonal frost. Climate warming is affecting spatiotemporal variations of snow and frost, hence influencing snowmelt infiltration, aquifer recharge and river runoff patterns. Measurement difficulties have hampered progress in properly assessing how variations in snow and frost impact snowmelt infiltration. This has led to contradicting findings. Some studies indicate that groundwater recharge response is scale dependent. It is thus important to measure snow and soil frost properties with temporal and spatial scales appropriate to improve infiltration process knowledge. The main aim with this paper is therefore to review ground based methods to measure snow properties (depth, density, water equivalent, wetness, and layering) and soil frost properties (depth, water and ice content, permeability, and distance to groundwater) and to make recommendations for process studies aiming to improve knowledge regarding infiltration in regions with seasonal frost. Ground-based radar (GBR) comes in many different combinations and can, depending on design, be used to assess both spatial and temporal variations in snow and frost so combinations of GBR and tracer techniques can be recommended and new promising methods (auocostics and self potential) are evolving, but the study design must be adapted to the scales, the aims and the resources of the study.
Abstract: Under rainfall conditions, aggregates may suffer breakdown by different mechanisms. Slaking is a very efficient breakdown mechanism. However, its occurrence under rainfall conditions has not been demonstrated. Therefore, the aim of this study was to evaluate the occurrence of slaking under rain. Two soils with silt loam (SL) and clay loam (CL) textures were analyzed. Two classes of aggregates were utilized: 1–3 mm and 3–5 mm. The aggregates were submitted to stability tests and to high intensity (90 mm·h−1) and low intensity (28 mm·h−1) rainfalls, and different kinetic energy impacts (large and small raindrops) using a rainfall simulator. The fragment size distributions were determined both after the stability tests and rainfall simulations, with the calculation of the mean weighted diameter (MWD). After the stability tests the SL presented smaller MWDs for all stability tests when compared to the CL. In both soils the lowest MWD was obtained using the fast wetting test, showing they were sensitive to slaking. For both soils and the two aggregate classes evaluated, the MWDs were recorded from the early beginning of the rainfall event under the four rainfall conditions. The occurrence of slaking in the evaluated soils was not verified under the simulated rainfall conditions studied. The early disaggregation was strongly related to the cumulative kinetic energy, advocating for the occurrence of mechanical breakdown. Because slaking requires a very high wetting rate on initially dry aggregates, it seems unlikely to occur under field conditions, except perhaps for furrow irrigation.
Abstract: Potential implications of rainfall variability along with Land Use and Land Cover Change (LULC) on stream flow have been assessed in the Black Volta basin using the SWAT model. The spatio-temporal variability of rainfall over the Black Volta was assessed using the Mann-Kendall monotonic trend test and the Sen’s slope for the period 1976–2011. The statistics of the trend test showed that 61.4% of the rain gauges presented an increased precipitation trend whereas the rest of the stations showed a decreased trend. However, the test performed at the 95% confidence interval level showed that the detected trends in the rainfall data were not statistically significant. Land use trends between the year 2000 and 2013 show that within thirteen years, land use classes like bare land, urban areas, water bodies, agricultural lands, deciduous forests and evergreen forests have increased respectively by 67.06%, 33.22%, 7.62%, 29.66%, 60.18%, and 38.38%. Only grass land has decreased by 44.54% within this period. Changes in seasonal stream flow due to LULC were assessed by defining dry and wet seasons. The results showed that from year 2000 to year 2013, the dry season discharge has increased by 6% whereas the discharge of wet season has increased by 1%. The changes in stream flows components such us surface run-off (SURF_Q), lateral flow (LAT_Q) and ground water contribution to stream flow (GW_Q) and also on evapotranspiration (ET) changes due to LULC was evaluated. The results showed that between the year 2000 and 2013, SURF_Q and LAT_Q have respectively increased by 27% and 19% while GW_Q has decreased by 6% while ET has increased by 4.59%. The resultant effects are that the water yield to stream flow has increased by 4%.
Abstract: Forestry operations can significantly alter hydrological and erosional processes in a catchment. In the course of developing timberland, a network of persistent roads and skid trails causing soil compaction is usually established. Hereby, the infiltration rate of the soil is distinctly reduced, which leads to the generation of overland flow—this may also cause soil erosion. In this study, a small-scale rainfall simulator is used to investigate hydrological and erosional processes on forest roads and skid trails. The results show increased runoff rates on forest roads, up to 25 times higher than on undisturbed forest topsoil. On skid trails, the runoff rates were altered especially in rutted areas (16 times higher) while unrutted parts showed a lesser change (four times higher). With sufficient overland flow, soil erosion rates also rose, particularly when the vegetation cover of the surface was removed: bare road surfaces featured higher mean erosion rates (195 g·m−2) than partly or completely vegetated skid trails (13 g·m−2) and undisturbed sites (5 g·m−2). The findings presented in this study indicate the need for the use of compaction reducing technology during forestry operations and a revegetation of road surfaces in order to minimize the detrimental factor of roads and skid trails on water retention and soil conservation.