Hydraulic Resistance of Vegetation in River Flow Applications

Proceedings of the Seventh International Conference on Hydroscience and Engineering, Philadelphia, PA, September 2006. http://hdl.handle.net/1860/732If vegetated regions become part of a river’s flow field, the hydraulic resistance of vegetation affects the overall conveyance. Several descriptions exist to describe this type of flow; among them are empirical relations and relations that are process-based. In the current work three expressions are considered that have equal input parameters, similar levels of complexity but different theoretical backgrounds. The performance of the three methods is evaluated by comparison with flow measurements (collected from literature), and limits are given for their practical use

Effect of vegetation growth in drainage canals on water management

In 2002 a new regulation was adopted in the Netherlands to protect flora and fauna. As a consequence mowing of drainage canals will be restricted during the growing season leading to vegetated canals that may hamper the discharge of water. In the summer of 2006 a field experiment has been executed in combination with a model study to investigate the effects of vegetation growth in the Fliert, a drainage canal located in the central part of the Netherlands. The field experiments showed extensive vegetation growth in absence of mowing. For the model study SOBEK Rural was used to evaluate different rainfall and vegetation (mowing) scenarios. From the model study it could be concluded that vegetation growth in combination with high rainfall can lead to water management problems. This means that if mowing is not allowed alternative measures are necessary. Unfortunately, model results could not be validated due to a relative dry summer

Agent-based modelling of cholera diffusion

This paper introduces a spatially explicit agent-based simulation model for micro-scale cholera diffusion. The model simulates both an environmental reservoir of naturally occurring V. cholerae bacteria and hyperinfectious V. cholerae. Objective of the research is to test if runoff from open refuse dumpsites plays a role in cholera diffusion. A number of experiments were conducted with the model for a case study in Kumasi, Ghana, based on an epidemic in 2005. Experiments confirm the importance of the hyperinfectious transmission route, however, they also reveal the importance of a representative spatial distribution of the income classes. Although the contribution of runoff from dumpsites can never be conclusively proven, the experiments show that modelling the epidemic via this mechanism is possible and improves the model results. Relevance of this research is that it shows the possibilities of agent-based modelling combined with pattern reproduction for cholera diffusion studies. The proposed model is simple in its setup but can be extended by adding additional elements such as human movement and change of behaviour of individuals based on disease awareness. Eventually, agent-based models will open opportunities to explore policy related research questions related to interventions to influence the diffusion process

Remediation of Contaminated Soils by Solvent Flushing

Solvent flushing is a potential technique for remediating a waste disposal/spill site contaminated with organic chemicals. This technique involves the injection of a solvent mixture (e.g., water plus alcohols) that enhances contaminant solubility, reduces the retardation factor, and increases the release rates of the contaminants. A simulation model is developed to predict contaminant elution curves during solvent flushing for the case of one‐dimensional, steady flow through a contaminated medium. Column experiments are conducted with a Eustis fine sand that is initially equilibrated with an aqueous naphthalene solution, and then eluted with different methanol‐water mixtures to remove the naphthalene. The model simulations, based on parameter values estimated from literature data, agree well with the measured elution profiles. Solvent flushing experiments, where the soil was initially equilibrated with a solution of naphthalene and anthracene, show that compounds with different retardation factors are separated at low cosolvent contents, while coelution of the compounds occurs at higher contents. In general, the smaller the retardation factor in water and the higher the cosolvent fraction, the faster the contaminant is recovered. The presence of nonequilibrium conditions, soil heterogeneity, and type of cosolvent will influence the time required to recover the contaminant.\u

Application of Sentinel-1 soil moisture information for improving groundwater simulations

To support robust water management, water managers should have access to up-to-date information about their water system. For example, Dutch regional water authorities are interested in temporally and spatially distributed groundwater level information. The Netherlands Hydrological Model LHM is often used for retrieving such information on several spatial scales in the Netherlands (De Lange et al., 2014). LHM is a physically-based distributed integrated hydrological model for simulating surface water, unsaturated zone and saturated zone dynamics. However, a validation of saturated zone simulations shows that, on a local to regional scale, deviations occur between observations and simulations of groundwater levels. The availability of high-resolution remotely sensed hydrological information has led to new possibilities for hydrological model improvements. Assimilating soil moisture information can improve both unsaturated and saturated zone simulations (Camporese et al., 2009; Zhang et al., 2016). Recently, a fine-resolution surface soil moisture product based on the freely available Sentinel-1 imagery has been developed. We use this new soil moisture information in combination with an Ensemble Kalman Filter to improve groundwater simulations of the LHM and to develop an accurate system for real-time groundwater simulations and forecasts. The open-source data assimilation framework OpenDA is used to implement the filter technique. The Twente region in the Netherlands serves as a case study. The availability of in-situ soil moisture and groundwater level measurement networks enables validation of the results. The results of this study show the potential of using high-resolution Sentinel-1 satellite imagery for water management. Water managers can use this knowledge to improve forecasts of groundwater levels and to estimate effects of control measures. Furthermore, water managers can use the results to explore the use of soil moisture information for water management. References Camporese, M., Paniconi, C., Putti, M., & Salandin, P. (2009). Ensemble Kalman filter data assimilation for a process-based catchment scale model of surface and subsurface flow. Water Resources Research, 45(10). doi:10.1029/2008wr007031. De Lange, W. J., Prinsen, G. F., Hoogewoud, J. C., Veldhuizen, A. A., Verkaik, J., Oude Essink, G. H. P., van Walsum,P.E.V.,Delsman,J.R.,Hunink,J.C.,Massop,H.T.L.,&Kroon,T.(2014).Anoperational,multi-scale, multi-model system for consensus-based, integrated water management and policy analysis: The Netherlands Hydrological Instrument. Environmental Modelling & Software, 59, 98-108. doi:10.1016/j.envsoft.2014.05.009. Zhang, D., Madsen, H., Ridler, M. E., Kidmose, J., Jensen, K. H., & Refsgaard, J. C. (2016). Multivariate hydrological data assimilation of soil moisture and groundwater head. Hydrology and Earth System Sciences

Reorganization of water and waste water management in Romania:from local to regional water governance

Romania's drinking water and wastewater sector is currently going through a process of regionalization. This process involves a replacement of a local-focused governance structure by a regional-focused governance structure. The objective of this paper is to explore and explain this regionalization from a governance perspective. In two case studies, the situation before and after the regionalization are investigated. Analyses of the case studies show that the local-focused governance structure was highly incoherent. This resulted in a lack of financial resources needed to maintain and develop the water infrastructure. Romania's accession to the European Union affected several governance elements and evoked the regionalization. Real improvements are not visible yet as the time needed for actual services improvements is considerable and governance elements are still adjusting to each other. This means that there is still a need for ongoing support to arrive at a coherent governance structure