The 3rd ISPRS Workshop on Dynamic and Multi-Dimensional GIS & the 10th Annual Conference of CPGIS on Geoinformatics

Chen, Jun

Bibliographic data

Monograph

Persistent identifier:: 856566209

Author:: Chen, Jun

Title:: The 3rd ISPRS Workshop on Dynamic and Multi-Dimensional GIS & the 10th Annual Conference of CPGIS on Geoinformatics

Sub title:: May 23 - 25, 2001, Bangkok, Thailand

Scope:: VI, 434 Seiten

Year of publication:: 2001

Place of publication:: Pathumthani, Thailand

Publisher of the original:: AIT

Identifier (digital):: 856566209

Illustration:: Illustrationen, Diagramme, Karten

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: MODELING LAND USE EFFECT ON URBAN STORM RUNOFF AT THE WATERSHED SCALE. Chansheng HE

Document type:: Monograph

Structure type:: Chapter

ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS’’, Bangkok, May 23-25, 2001 130 2.3 Execution of AGNPS The entire Dowagiac River Watershed is divided into 4803 cells, with the size of each cell equal to 40 acres (16 ha). Digital elevation data at a scale of 1: 250,000 were acquired from the U.S. Geological Survey. State Soil Geographic Data Base (STATSGO) was obtained from the U.S. Department of Agriculture Natural Resource Conservation Service. The watershed boundary was acquired from the Michigan Department of Environmental Quality Hydrologic Studies Unit. Land use/cover data of 1978-1981, the only data available for the study area, were obtained from the Michigan Resource Information System (MjRIS) for the entire Dowagiac River Watershed. The single storm event chosen in the model was a 24-hour rainfall of 4.5 inches with an exceedance probability of 4 percent (recurrence interval of 25 years) from the Dowagiac Weather Station (Sorrel and Hamilton 1990). In the Dowagiac River Watershed, this type of storm usually occurs in the summer months (June through August). The AVNPSM was used to derive all the 22 input parameters and generate an input file for the AGNPS model. AGNPS Version 5.0 was run to produce estimates of surface runoff, soil erosion and sediment, and nutrient loadings. 3.SIMULATION OF LAND USE CHANGE SCENARIO AND ITS IMPACT ON WATER QUALITY Residential and commercial developments are reportedly considered as the two most important land use issues in the Dowagiac River Watershed according to a joint report by the Cass County Conservation District, Michigan Department of Environmental Quality and Southwestern Michigan Commission (1998). Several townships are reported to .likely have population growth of more than 10 percent during the period of 2000-2010. Accompanying the projected population growth comes increasing demands for residential housing and commercial services. These demands will likely lead to conversion of some agricultural, forest, and nonforest vegetation (grassland) to residential and commercial lands. To help resource planners and managers understand the potential impacts of these developments on water quality in the Dowagiac River, a land use change scenario is simulated and its water quality effect is analyzed by using the AGNPS model. The simulated land use change scenario is to convert the northwest corner of the La Grange Township to residential and commercial developments because it is adjacent to the City of Dowagiac and very likely to face residential and commercial expansion issues in the next decade. The selected area is about 1,400 acres (560 ha) and includes urban, agricultural, nonforest vegetation, forest, and forested wetland. Conversion of this area to urban land represents an expansion of the current urban land by about 1240 acres. Assuming all other factors remaining same, the AGNPS model was run to simulate the effect of the changed land use on water quality and the result is summarized in Table 1. As shown in Table 1, conversion of about 1,240 acres of non- urban land to urban land is simulated to cause little increase in the peak flow rate and sediment yield at the mouth of the river but has almost no impact on runoff volume and nutrient yields (Fig.2). This is probably due to the fact hat the size of the proposed land use change was too small to have any impact at the watershed level. If more land in the watershed is converted to urban uses, it might lead to greater changes in discharge and sediment yield at the outlet of the watershed. In addition, the hydrologic effects are related to the types of land use change and the locations of the changes. The simulated land use change is in the northwest corner of the La Grange Township, adjacent to the City of Dowagiac. If the land use changes were to occur in areas adjacent to a waterbody such as a lake or river, Table 1. Summary of the Impact of the Simulated Land Use Change in La Grange Township on Runoff, Sediment, and Nutrients at the Outlet of the Dowagiac River Watershed from a Single Storm Event of 4.5 in. Variable Simulated Result Using the Baseline Data Simulated Result Using the Proposed Land Use Scenario 25-Year Recurrence, 24-hour Storm (inches) 4.50 4.50 Surface Runoff (inches) 1.82 1.82 Peak Flow Rate (cfs) 3,231 3,235 Total Sediment Yield (tons) 9,985 9.992 Total N in Sediment (Ibs/acre) 0.85 0.85 Total P in Sediment (Ibs/acre) 0.43 0.43 greater impact on water quality would have produced. In simulating the effect of urban land expansion on water quality, this study assumed the land cover is the only variable to be changed and all other factors such as soil, topography, and management practices are to remain unchanged. In reality, urban development often causes changes in some related factors such as topography and landscape irrigation. The simulated magnitude of the land use change impact on water quality should be evaluated using the field data in order to support the informed land use decision making process. Resource planners and decision makers should also realize that the location of the land use change such as proximity to a waterbody has significant impact on water quality and need to consider this factor in dealing with the land use issues in the Dowagiac River Watershed. 4.SUMMARY AND CONCLUSIONS This study integrates AGNPS and digital databases of soil, land cover/use, topography, water resource features and management practices to simulate the impact of land use change scenario on runoff, sediment, and nutrient yields based on a 25-year, 24-hour period of single storm event of 4.5 inches in the entire Dowagiac River Watershed. The simulation results show that expansion of urban land will probably lead to an increase in surface runoff, peak flow, and soil erosion. The magnitude of the effect is related to the extent and proximity of proposed land use change to water bodies in the watershed. AGNPS requires 22 input parameters. Manual input of these input parameters for each of the 4,803 cells in the Dowagiac River Watershed would be time consuming, tedious, and problematic. This study develops AVNPSM, an interface between ArcView and AGNPS to derive, analyze, and visualize the required model parameters and simulated results from the databases of soil, topography, land cover, and water resource features. The interface consists of parameter generator, input file processor, model executor, output visualizer, statistical analyzer, and land use change simulator. Application of the interface to the study watershed indicates that it is user friendly, and robust, and significantly improves the efficiency of the nonpoint source pollution modeling process. With the interface, land use change scenarios can be readily explored in the model to help resource planners and decision makers develop watershed management plan to minimize sedimentation and nutrient loading to the receiving waters.

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