Chris S. Renschler

Soil erosion assessment tools from point to regional scales: the role of geomorphologists in land management research and implementation

Geomorphological research has played an important role in the development and implementation of soil erosion assessment tools. Because policy and management approaches include the use of soil erosion assessment tools, soil erosion research directly affects the public in terms of providing information on natural hazards and human impacts, and also as the basis for regulatory policy on land management. For example, soil loss calculations and geomorphological expertise are used to support soil conservation planning, both through agricultural legislation that defines maximum tolerable soil loss rates, and through federal and local legislation that requires soil erosion controls on many construction sites. To be useful for decision makers, soil erosion models must have simple data requirements, must consider spatial and temporal variability in hydrological and soil erosion processes, and must be applicable to a variety of regions with minimum calibration. The growing use of erosion models and Geographic Information Systems (GIS) in local to regional scale soil and water conservation raises concerns about how models are used. This has prompted interest in methods to assess how models function at management scales and with the types of data that are commonly available to users. A case study of a GIS-based soil erosion assessment tool using the process-based Water Erosion Prediction Project (WEPP) shows that using commonly available data rather than research grade data can have (predictably) a significant impact on model results. If model results are then used in management decisions, it is critical to assess whether the scale and direction of variation in results will affect management and policy decisions. Geomorphologists provide unique perspectives on soil erosion and can continue to affect policy through soil erosion research. This research should focus on fundamental processes, but equally important is continued development and evaluation of models that are matched to real world data availability, geomorphic settings, and information needs. D 2002 Elsevier Science B.V. All rights reserved.

Evaluating spatial and temporal variability in soil erosion risk—rainfall erosivity and soil loss ratios in Andalusia, Spain

Abstract Erosion modeling techniques provide a framework for the evaluation of agricultural impacts on soil and water resources. Agricultural policies or economic incentives generally induce land use changes or even agricultural crop rotation changes. This results in a different erosional behavior of cultivated soil. Besides economic benefits, the sustainability of the agricultural practices with regard to soil and water resources has to be evaluated for specific local or regional conditions. This paper analyzes the spatial and temporal variability in soil erosion risks in a changing Mediterranean agro-ecological situation. At first the spatio-temporal variability of rainfall erosivity is analyzed. The depth and erosivity of design storms are determined for different return periods. Then, the temporal variability of soil loss ratios (SLR) due to different agricultural crop rotations are evaluated on watershed scale using the revised universal soil loss equation (RUSLE). The 211 km 2 Guadalteba river basin and study area is located in the region of Andalusia, southern Spain, presenting a typical south European agricultural wheat and oil producing area with marked occurrence of soil erosion problems. The spatial soil erosion risk evaluation approach is based on commonly available data and a minimum of additional field observations. The spatial distribution of input and output data is handled with the Integrated Land and Water Information System (ILWIS).

SITE-SPECIFIC DECISION-MAKING BASED ON RTK GPS SURVEY AND SIX ALTERNATIVE ELEVATION DATA SOURCES: WATERSHED TOPOGRAPHY AND DELINEATION

Soil erosion modeling and assessment requires substantial and accurate topographic data to obtain meaningful results for decision–making regarding soil and water conservation practices. Today’s precision farming equipment includes Global Positioning System (GPS) technology to determine the location of spatially distributed data. Besides the main purpose of tagging site–specific information to a unique location (x and y), the elevation data (z) recorded has the potential to be used for topographic analysis, including delineation of flowpaths, channels, and watershed boundaries. In addition to GPS–based data collection at various accuracy levels, surveying companies and the U.S. Geological Survey also provide alternative sources of topographic information. Spatial statistical tests were performed to determine if some of these data sources . in particular the ones free of charge or gathered with inexpensive equipment . are sufficiently accurate to represent field or watershed topography and meaningfully apply detailed, process–based soil erosion assessment tools. The most expensive alternatives were most useful for determining elevation and slopes in the flow direction, while there was not much difference between alternatives in obtaining upslope drainage areas and delineation of the channel network and watershed boundary. This is the first of two articles analyzing the impact of the accuracy of six alternative topographic data sources on watershed topography and delineation in comparison to GPS measurements using a survey–grade cm–accuracy GPS.

Geospatial Disaster Response during the Haiti Earthquake: A Case Study Spanning Airborne Deployment, Data Collection, Transfer, Processing, and Dissemination

Immediately following the 12 January 2010 earthquake in Haiti, a disaster response team from Rochester Institute of Technology, ImageCat Inc., and Kucera International, funded by the Global Facility for Disaster Reduction and Recovery group of the World Bank, collected 0.15 m airborne imagery and two points/m2 lidar data for 650 km2 over a period of seven days. Data were transferred to Rochester, New York for processing at rates that approached 400 Mb/s using Internet2, ortho-rectified with a 24-hour turnaround, and distributed to response agencies through file or disk transfer. A unique response effort, dubbed the Global Earth Observation - Catastrophe Assessment Network (GEO-CAN) and headed by ImageCat, utilized over 600 experts from 23 different countries to generate rapid turnaround damage assessment products. This paper highlights the airborne data collection, transfer, processing, and product development effort, which arguably has raised the bar in terms of response to large-scale disasters.

PEOPLES: A Framework for Evaluating Resilience

AbstractIn recent years, the concept of resilience has been introduced to the engineering field in particular related to disaster mitigation and management. However, the built environment is only part of the elements that support community functions. Maintaining community functionality during and after a disaster, defined as resilience, is influenced by multiple components. The paper is proposing a framework for measuring community resilience at different spatial and temporal scales. Seven dimensions are identified for measuring community resilience: population and demographics, environmental and ecosystem, organized governmental services, physical infrastructures, lifestyle and community competence, economic development, and social-cultural capital. They are summarized with the acronym PEOPLES. Each dimension is characterized by a corresponding performance metric that is combined with the other dimensions using a multilayered approach. Therefore, once a hybrid model of the community is defined, the propo...

Regionalisation concept for hydrological modelling on different scales using a physically based model: Results and evaluation

Abstract A regionalisation concept for hydrological modelling on different scales using a physically based simulation model is presented. It enables us to calculate regional water balances by simulating a limited number of representative ecotopes (=hydro-pedotopes) instead of all units using a physically based model system (soilvegetation-atmosphere-transfer-scheme). Using a cluster analysis the hydrological quantities (e.g. monthly values of actual evapotranspiration, groundwater recharge, surface runoff and interflow of all ecotopes were analysed and groups of similar behaviour defined. For each of these clusters one representative ecotope is chosen. Results of an application of this concept are presented: The water fluxes of a 1000 km2 catchment in Germany were calculated and simulated runoff compared with measured. Simulating selected representative instead of all ecotopes reduces the number of necessary simulation runs by up to 95%. The results suggest that the quality of the simulation is not effected by using representative instead of all ecotopes. Because the data were not aggregated the spatial pattern of properties and fluxes is preserved. In order to evaluate the model results, the uncertainties concerning the data base (e.g. soil map, weather data) and the assumptions included in the regionalisation concept are investigated. Because in this concept no model calibration is performed, the applicability is only limited by the data availability (spatial and temporal resolution). The model shows a reliable hydrological behaviour and is a suitable tool for landscape management.

Geospatial Application of the Water Erosion Prediction Project (WEPP) Model

Abstract. At the hillslope profile and/or field scale, a simple Windows graphical user interface (GUI) is available to easily specify the slope, soil, and management inputs for application of the USDA Water Erosion Prediction Project (WEPP) model. Likewise, basic small watershed configurations of a few hillslopes and channels can be created and simulated with this GUI. However, as the catchment size increases, the complexity of developing and organizing all WEPP model inputs greatly increases due to the multitude of potential variations in topography, soils, and land management practices. For these types of situations, numerical approaches and special user interfaces have been developed to allow for easier WEPP model setup, utilizing either publicly available or user-specific geospatial information, e.g., digital elevation models (DEMs), geographic information system (GIS) soil data layers, and GIS land use/land cover data layers. We utilize the Topographic Parameterization (TOPAZ) digital landscape analysis tool for channel, watershed, and subcatchment delineation and to derive slope inputs for each of the subcatchment hillslope profiles and channels. A user has the option of specifying a single soil and land management for each subcatchment or utilizing the information in soils and land use/land cover GIS data layers to automatically assign those values for each grid cell. Once WEPP model runs are completed, the output data are analyzed, results interpreted, and maps of spatial soil loss and sediment yields are generated and visualized in a GIS. These procedures have been used within a number of GIS platforms including GeoWEPP, an ArcView/ArcGIS extension that was the first geospatial interface to be developed in 2001. GeoWEPP allows experienced GIS users the ability to import and utilize their own detailed DEM, soil, and/or land use/land cover information or to access publicly available spatial datasets. A web-based GIS system that used MapServer web GIS software for handling and displaying the spatial data and model results was initially released in 2004. Most recently, Google Maps and OpenLayers technologies have been integrated into the web WEPP GIS software to provide significant enhancements. This article discusses in detail the logic and procedures for developing the WEPP model inputs, the various WEPP GIS interfaces, and provides example real-world geospatial WEPP applications. Further work is ongoing in order to expand these tools to allow users to customize their own inputs via the internet and to link the desktop GeoWEPP with the web-based GIS system.

GeoWEPP - The Geo-spatial interface for the Water Erosion Prediction Project

Decision-makers operating at different scales of interest and responsibility have to assess the distribution, extent, and severity of soil erosion and sedimentation. To seek solutions in handling natural and human actions related to this type of nonpoint source pollution, the linkage of distributed assessment models and Geographical Information Systems (GIS) at various spatial and temporal scales is in high demand. The Water Erosion Prediction Project (WEPP) model is a continuous simulation, process-based model that allows simulation of water and sediment balance in small watersheds and on hillslope profiles within those watersheds. This presentation introduces an approach for running WEPP simulations based on using available geo-spatial information through a linkage with GIS. The new Geo-spatial interface for WEPP (GeoWEPP) utilizes readily available digital geo-referenced information from publicly accessible Internet sources such as the U.S. Geological Survey digital elevation models, topographical maps, and land use data as well as Natural Resources Conservation Service soils maps. Together with parameter sets of the WEPP database containing statistical parameter sets from more than 2600 U.S. climate stations, GeoWEPP enables even non-GIS-and-modeling users to derive and prepare valid model input parameters to assess representative conditions in an area of interest. After establishing the main data input for a particular site, various land use scenarios can be evaluated to assist with soil and water conservation planning.

A formal model to infer geographic events from sensor observations

The Sensor Web provides wider access to sensors and their observations via the Web. A key challenge is to infer information about geographic events from these observations. A systematic approach to the representation of domain knowledge is vital when reasoning about events due to heterogeneous observational sources. This article delivers a formal model capturing the relations between observations and events. The model is exploited with a rule-based mechanism to infer information about events from in-situ observations. The article also describes how the model’s vocabularies are used to formulate spatiotemporal queries. A use case for reasoning about blizzard events based on real time series illustrates the formal model.

Evaluating post-disaster ecosystem resilience using MODIS GPP data.

Abstract An integrated community resilience index (CRI) quantifies the status, exposure, and recovery of the physical, economic, and socio-cultural capital for a specific target community. However, most CRIs do not account for the recovery of ecosystem functioning after extreme events, even though many aspects of a community depend on the services provided by the natural environment. The primary goal of this study was to monitor the recovery of ecosystem functionality (ecological capital) using remote sensing-derived gross primary production (GPP) as an indicator of ‘ecosystem-wellness’ and assess the effect of resilience of ecological capital on the recovery of a community via an integrated CRI. We developed a measure of ecosystem resilience using remotely sensed GPP data and applied the modeling prototype ResilUS in a pilot study for a four-parish coastal community in southwestern Louisiana, USA that was impacted by Hurricane Rita in 2005. The results illustrate that after such an extreme event, the recovery of ecological capital varies according to land use type and may take many months to return to full functionality. This variable recovery can potentially impact the recovery of certain businesses that rely heavily on ecosystem services such as agriculture, forestry, fisheries, and tourism.