Analyse des Systèmes, Evaluation Intégrée et Modélisation
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GIS analysis and optimisation of faecal sludge logistics at city-wide scale in Kampala, Uganda
The majority of residents in low- and middle-income countries are served by onsite sanitation. Equitable access to sanitation, including emptying, collection, and transport services for the accumulation of faecal sludge remains a major challenge. Comprehensive information on service coverage by mechanical faecal sludge emptying service providers is lacking. The purpose of this study is to analyse the spatial distribution of service coverage and identify areas without faecal sludge emptying services in Kampala, Uganda. The study uses GIS (geographic information systems) as a tool to analyse real-time data of service providers based on GPS (global positioning system) units that were installed in a representative number of trucks. Of the total recorded 5653 emptying events, 27% were located outside Kampala city boundaries. Of those within Kampala city boundaries, 37% were classified as non-household customers. Areas without service provision accounted for 13% of the total area. Service provision normalised by population density revealed much greater service provision in medium- and high-income areas than low- and very low-income areas. The employed method provides a powerful tool to optimise faecal sludge management on a city-wide scale by increasing sustainability of the planning and decision-making process, increasing access to service provision and reducing faecal sludge transport times and costs.
Schoebitz, L.; Bischoff, F.; Lohri, C. R.; Niwagaba, C. B.; Siber, R.; Strande, L. (2017) GIS analysis and optimisation of faecal sludge logistics at city-wide scale in Kampala, Uganda, Sustainability, 9(2), 194 (16 pp.), doi:10.3390/su9020194, Institutional Repository
GIS-Dokumentation zur Thematischen Synthese 2 „Bewirtschaftung der Wasserressourcen unter steigendem Nutzungsdruck“ im Rahmen des Nationalen Forschungsprogramms 61 (NFP 61)
Im Rahmen der Thematischen Synthese „Bewirtschaftung der Wasserressourcen unter steigendem Nutzungsdruck“ (Thematische Synthese 2 (TS 2)) des Nationalen Forschungsprogramms 61 „Nachhaltige Wassernutzung“ wurden Nutzungsüberlagerungen im Wasserbereich der Schweiz und die sich daraus ergebenden Konflikte und Synergien systematisch untersucht. Zu diesem Zweck wurden verschiedenste GIS-Datensätze zusammengetragen, miteinander verschnitten und z.T. neu dargestellt. Im Folgenden sind die im Bericht verwendeten GIS-Karten (Tab. 1) mitsamt Bildlegenden nochmals wiedergegeben und mit ihren Datengrundlagen und Auswertungen methodisch beschrieben. In Tabelle 2 sind weitere Karten aufgeführt, auf welche im Bericht verwiesen wird.
Rahn, E.; Siber, R.; Lanz, K.; Stamm, C. (2014) GIS-Dokumentation zur Thematischen Synthese 2 „Bewirtschaftung der Wasserressourcen unter steigendem Nutzungsdruck“ im Rahmen des Nationalen Forschungsprogramms 61 (NFP 61), 11 p, Institutional Repository
Ereignisbezogenes Pestizidmonitoring. Am Beispiel der Gürbe (Kanton Bern)
Der Kanton Bern startete 2008 das Projekt «Gewässerzustand im Aaretal» (GZA), um Fragen zum Fischrückgang zu klären und Beeinträchtigungen der Wasserqualität durch Schadstoffe wie Pestizide zu untersuchen. Die Ergebnisse des Pestizidmonitorings entsprechen für die meisten landwirtschaftlichen Pestizide den Erwartungen: Die Konzentrationen steigen während Abflusereignissen an. Allerdings zeigte sich auch, dass Biozide und Pestizide aus urbanen Quellen höhere Konzentrationsspitzen verursachen.
Stamm, C.; Siber, R.; Singer, H.; Ochsenbein, U.; Berset, J.-D.; Scheiwiller, E.; Muff, D. (2012) Ereignisbezogenes Pestizidmonitoring. Am Beispiel der Gürbe (Kanton Bern), Aqua & Gas, 92(4), 24-32, Institutional Repository
MapRank: Geographical search for cartographic materials in libraries
Searches for cartographic materials have previously been carried out using conventional library search systems. However, this kind of search method often proves to be inadequate, as the lack of suitable user interfaces means that queries have to be formulated in words. Furthermore, indexing based on geographical names does not adequately describe the spatial dimension of cartographic material, and geographical names also tend to be ambiguous and inclined to change. A web-based geographical search system (geosearch), which analyzes the geographical coordinates of MARC21 field 034, has been developed for the Swiss research portal for maps. The geosearch enables cartographic material to be found quickly and efficiently on the basis of its location and spatial extent via an intuitively accessible user interface. This is achieved with a cleverly devised ranking algorithm (MapRank®) and an innovative indexing mechanism. The number of search results can also be restricted by applying filters relating to the publication period and map scale. The geosearch is proving to be a powerful search tool which, in an open-ended search scenario, can be used to find roughly double the amount of relevant cartographic material within a short space of time. The system is intuitive to operate and no previous knowledge is required. It also offers further strengths, such as the ability to search through extremely large quantities of data quickly and independently from the various subject heading systems and thesauri. This makes the geosearch an ideal tool for carrying out map searches in metacatalogs.
Although herbicides can be detected in surface waters throughout Switzerland, herbicide-intensive crops are mainly cultivated in low-risk areas. This was shown by an assessment involving GIS-based modelling of discharge processes on the Central Plateau. With this approach, critical areas can also be identified.
Siber, R. (2011) Where is herbicide use particularly critical?, Eawag News [engl. ed.], 71, 14-17, Institutional Repository
Modeling potential herbicide loss to surface waters on the Swiss plateau
Lack of sufficiently detailed data often limits the applicability of complex transport-reaction models for estimating potential herbicide loss to surface waters. Therefore, there is also a need for simple models that are easy to apply but still capture the main features of the underlying processes.
In this study, a simple regression model was developed to assess the vulnerability of catchments in the Swiss Plateau to diffuse herbicide loss to surface waters. The model is designed as a screening tool to rank the catchments in a relative sense and not to calculate Predicted Environmental Concentrations (PEC) of pesticides. The main goal is to capture two dominating factors controlling diffuse herbicide transport into streams and rivers. These factors are herbicide application and fast flow processes that are mainly responsible for herbicide transport. In a first step vulnerability of sites to herbicide loss is estimated based on site-specific conditions irrespective of actual herbicide application. In the second step, this vulnerability assessment is combined with actual herbicide application data to estimate the potential herbicide loss.
The fast flow index (FFI), derived from discharge data using a base flow separation method, was applied as a proxy for the amount of fast flow occurring. The influence of catchment attributes (including topographic, climatic and soil data) on the FFI was analyzed using a multiple regression approach based on data from 57 catchments of the Swiss Plateau. By combining regression analysis with mechanistic knowledge, a two factor non-linear model based on river density and soil permeability as dominant input factors was selected as the best model for FFI prediction given the available data. Higher dimensional models had to be excluded because the strong correlation between the potential input factors led to unrealistic dependences while only minimally improving the quality of the fit.
The spatial pattern of the predicted FFI as a measure for the vulnerability to diffuse herbicide losses shows a clearly increasing trend from the western to the eastern part of the Swiss Plateau and towards the pre-alpine/alpine regions in the south.
In general the pattern of herbicide use corresponds to site conditions typical of a low FFI. However, the spatial analysis revealed exceptions, namely areas in which high actual herbicide use coincides with a high FFI.
Despite the uncertainties in the model, this simple approach seems to be useful for supporting site-adapted agricultural practice whenever the higher accuracy of more detailed models is not required or too expensive to achieve. In addition, in combination with data on actual herbicide application, it can support the design of monitoring strategies by identifying critical areas of actual herbicide loss.
Tockner, K.; Uehlinger, U.; Robinson, C. T.; Siber, R.; Tonolla, D.; Peter, F. D. (2009) European Rivers, In: Likens, G. E. (Eds.), Encyclopedia of Inland Waters, 366-377, Institutional Repository
Modelling hydrology and water quality in the pre-alpine/alpine Thur watershed using SWAT
Summary In a national effort, since 1972, the Swiss Government started the "National Long-term Monitoring of Swiss Rivers" (NADUF) program aimed at evaluating the chemical and physical states of major rivers leaving Swiss political boundaries. The established monitoring network of 19 sampling stations included locations on all major rivers of Switzerland. This study complements the monitoring program and aims to model one of the program's catchments – Thur River basin (area 1700 km2), which is located in the north-east of Switzerland and is a direct tributary to the Rhine. The program SWAT (Soil and Water Assessment Tool) was used to simulate all related processes affecting water quantity, sediment, and nutrient loads in the catchment. The main objectives were to test the performance of SWAT and the feasibility of using this model as a simulator of flow and transport processes at a watershed scale. Model calibration and uncertainty analysis were performed with SUFI-2 (Sequential Uncertainty FItting Ver. 2), which was interfaced with SWAT using the generic iSWAT program. Two measures were used to assess the goodness of calibration: (1) the percentage of data bracketed by the 95% prediction uncertainty calculated at the 2.5 and 97.5 percentiles of the cumulative distribution of the simulated variables, and (2) the d-factor, which is the ratio of the average distance between the above percentiles and the standard deviation of the corresponding measured variable. These statistics showed excellent results for discharge and nitrate and quite good results for sediment and total phosphorous. We concluded that: in watersheds similar to Thur – with good data quality and availability and relatively small model uncertainty – it is feasible to use SWAT as a flow and transport simulator. This is a precursor for watershed management studies.
Abbaspour, K. C.; Yang, J.; Maximov, I.; Siber, R.; Bogner, K.; Mieleitner, J.; Zobrist, J.; Srinivasan, R. (2007) Modelling hydrology and water quality in the pre-alpine/alpine Thur watershed using SWAT, Journal of Hydrology, 333(2–4), 413-430, doi:10.1016/j.jhydrol.2006.09.014, Institutional Repository
Consequences of climatic change for water temperature and brown trout populations in Alpine rivers and streams
Twenty-five years of extensive water temperature data show regionally coherent warming to have occurred in Alpine rivers and streams at all altitudes, reflecting changes in regional air temperature. Much of this warming occurred abruptly in 1987/1988. For brown trout populations, the warming resulted in an upward shift in thermal habitat that was accelerated by an increase in the incidence of temperature-dependent Proliferative Kidney Disease at the habitat's lower boundary. Because physical barriers restrict longitudinal migration in mountain regions, an upward habitat shift in effect implies habitat reduction, suggesting the likelihood of an overall population decrease. Extensive brown trout catch data documenting an altitudinally dependent decline indicate that such a climate-related population decrease has in fact occurred. Our analysis employs a quantitatively defined reference optimum temperature range for brown trout, based on the sinusoidal regression of seasonally varying field data