Klaus J.,TU Munich |
Klaus J.,Oregon State University |
Zehe E.,Basin Water
Hydrology and Earth System Sciences | Year: 2011
The present study tests whether an explicit treatment of worm burrows and tile drains as connected structures is feasible for simulating water flow, bromide and pesticide transport in structured heterogeneous soils at hillslope scale. The essence is to represent worm burrows as morphologically connected paths of low flow resistance in a hillslope model. A recent Monte Carlo study (Klaus and Zehe, 2010, Hydrological Processes, 24, p. 1595-1609) revealed that this approach allowed successful reproduction of tile drain event discharge recorded during an irrigation experiment at a tile drained field site. However, several "hillslope architectures" that were all consistent with the available extensive data base allowed a good reproduction of tile drain flow response. Our second objective was thus to find out whether this "equifinality" in spatial model setups may be reduced when including bromide tracer data in the model falsification process. We thus simulated transport of bromide for the 13 spatial model setups that performed best with respect to reproduce tile drain event discharge, without any further calibration. All model setups allowed a very good prediction of the temporal dynamics of cumulated bromide leaching into the tile drain, while only four of them matched the accumulated water balance and accumulated bromide loss into the tile drain. The number of behavioural model architectures could thus be reduced to four. One of those setups was used for simulating transport of Isoproturon, using different parameter combinations to characterise adsorption according to the Footprint data base. Simulations could, however, only reproduce the observed leaching behaviour, when we allowed for retardation coefficients that were very close to one. © Author(s) 2011.
Vijayaraghavan K.,Basin Water |
Winnie H.Y.N.,National University of Singapore |
Balasubramanian R.,National University of Singapore
Desalination | Year: 2011
This work explores the potential of crab (Portunus sanguinolentus) shell particles for the removal of manganese(II) and zinc(II) ions from aqueous solutions. The removal of metal ions by crab shell was found to be pH dependent, with optimum sorption occurring at pH 6 for both Mn(II) and Zn(II). The mechanism of metal removal by crab shell was identified as micro-precipitation of metal carbonates followed by adsorption onto chitin at the surface of crab shell, which was confirmed by pH edge and EDX analysis. The process of metal biosorption was rapid (90% removal in 120. min for Mn(II) and 90% removal in 90. min for Zn(II)) at an initial metal concentration of 500. mg/L. Modeling results revealed that Mn(II) and Zn(II) kinetics data were successfully described using pseudo-first and -second order models, compared to the Elovich equation. Furthermore, isotherm experiments revealed that crab shell possesses high uptake capacities of 69.9 and 123.7. mg/g for Mn(II) and Zn(II), respectively, according to the Langmuir model. Possibility of desorption and subsequent reuse of crab shell was attempted using 0.1. M HCl as elutant and the results were successful with the elutant exhibiting more than 99% elution efficiency for both Mn(II) and Zn(II). © 2010 Elsevier B.V.
Krone R.,Alfred Wegener Institute for Polar and Marine Research |
Gutow L.,Alfred Wegener Institute for Polar and Marine Research |
Joschko T.J.,University of Koblenz-Landau |
Schroder A.,Basin Water
Marine Environmental Research | Year: 2013
In the light of the introduction of thousands of large offshore wind power foundations into the North Sea within the next decades, this manuscript focuses on the biofouling processes and likely reef effects. The study explores the macrozoobenthos (biofouling) colonization at an offshore platform which is comparable to offshore wind turbine foundations. A total of 183 single samples were taken and the parameters water depth and time were considered comparing biofouling masses and communities. The blue mussel Mytilus edulis, Anthozoa and the Amphipoda Jassa spp. were the dominant species. The community from the 1 m zone and those from the 5 and 20-28 m zones can clearly be differentiated. The 10 m zone community represents the transition between the M. edulis dominated 1 m and 5 m zones and the Anthozoa dominated 20-28 m zone. In the future offshore wind farms, thousands of wind turbine foundations will provide habitat for a hard bottom fauna which is otherwise restricted to the sparse rocky habitats scattered within extensive sedimentary soft bottoms of the German Bight. However, offshore wind power foundations cannot be considered natural rock equivalents as they selectively increase certain natural hard bottom species. The surface of the construction (1280 m2) was covered by an average of 4300 kg biomass. This foundation concentrates on its footprint area (1024 m2) 35 times more macrozoobenthos biomass than the same area of soft bottom in the German exclusive economic zone (0.12 kg m-2), functioning as a biomass hotspot. Concerning the temporal biomass variation, we assume that at least 2700 kg biomass was exported on a yearly basis. 345 × 104 single mussel shells of different sizes were produced during the study period. It is anticipated that the M. edulis abundance will increase in the North Sea due to the expansion of the offshore wind farm development. This will result in the enhanced production of secondary hard substrate (mussel shells) and its associated fauna and will intensify filtration rates of the seawater. This predicted ecological system change is coined the 'Mytilusation' of the German Bight. © 2012 Elsevier Ltd.
Dessalegn M.,Basin Water
Water Alternatives | Year: 2015
In sub-Saharan Africa, motor pump irrigation is at an earlier stage than in Asia but is growing rapidly in many countries. The focus of both policy and research in Africa to date has been on facilitating supply chains to make pumps available at a reasonable price. In Africa, pump irrigation is mainly based on two sources: shallow groundwater aquifers and small streams and rivers. Both usually have limited and variable yields. We present a case study from Ethiopia where pump irrigation based on small rivers and streams is expanding rapidly, and draw parallels to experiences in Asia and other African countries. We show that while farmers understand the social nature of community-managed irrigation, they share with policymakers a narrow understanding of pump irrigation as being primarily 'technical'. They perceive pumps as liberating them from the 'social' limitations of traditional communal irrigation. However, the rapid expansion of pump irrigation is leading to increasing competition and conflict over the limited water resource. We analyse the wider implications for Africa of this blindness to the social dimension of pump irrigation and offer suggestions on future policy and applied research to address the problem before it becomes a widespread crisis.
Omedas-Margeli M.,Basin Water
International Journal of Water Resources Development | Year: 2011
Water management professionals generally recognize that the management of water in rivers and aquifers is more efficient and sustainable at the river basin level than at the political and administrative levels of regional administrations. The development and consolidation of the river basin authorities has not been without difficulties. Experience has shown that the Spanish river basin confederations, the French water agencies and the US valley authorities have been successful. There have also, however, been failures, many attributable to the difficulties of separating the political power of regions and nation-states. In the Ebro River Basin, integrated water resources management was applied even when it crossed the administrative borders of the Autonomous Communities; otherwise, the water produced by the Ebro would be one-quarter of its current volume. Thanks to the integrated management, the Ebro economic region is supplied by major reservoirs, especially the Ebro reservoir. Its major irrigation systems, the Aragón and Catalonia Canal, Bardenas, the Ebro Delta and others, are projects that were conceived under the principle of integrated water management. © 2011 Taylor & Francis.