A STUDY ON THE CONTROL OF WATER FLOW AT THE NEW SITE OF ADAMAWA STATE UNIVERSITY MUBI
By
AMINU ABDULWAHAB1,BELLO ALI GARBA,2 GUNDIRI I. ABALIS3 RAJI M. OLAYINKA4
A Project Report Submitted To Geoqinetiq Geomatics Gold Medal And Prize Advisory Board
FROM THE DEPARTMENT OF SURVEYING AND GEOINFORMATICS FEDERAL POLYTECHNIC MUBI, P.M.B 35, ADAMAWA STATE.
Alaminabdo53@gmail.com
ABSTRACT. This research work is a product of a preliminary watershed Analysis for the new virgin land of Adamawa State University, and it covers an area of approximately 650 hectares. The purpose of the research work is to describe what is not known about the condition of the new site and also to present a list of prioritized issues for the planners in their development of strategies for further assessment and subsequent watershed protection and restoration. The research examines land use history, boundary limit, direction of water flow, topology of the land, water quality, soil condition and social and economical conditions. As in the case of tropical countries, heavy rainfall and effect of the upstream change in land use have caused detrimental consequences in the sedimentation. Watershed analysis is recognized presently as the most suitable tool to manage and control the flow of water in the research area. Furthermore, the evaluation of processes that affect ecosystem and resources in a watershed is now being carried out by a surveying student, although, the methods to be used will differ from those of other implementations of watershed analysis because objectives and opportunities differ. In particular, Adamawa State University Management must take into account the full range of uses and values present. Interagency watershed analysis to include wildlife, social and economical components in addition to the physical and aquatic evaluations shared by other watershed analysis efforts. Interagency watershed analysis is intended to describe process interactions, GIS approach and ecosystem functions that shape the environment. This research work will be based primarily on the newly acquired information. It is an exercise in data gathering and inventory. The first wave of analysis is to show the major operational difficulties and to integrate information into or from multiple disciplines into an interdisplinary analysis. This research work will also focus on providing all the necessary information needed relating to the impact of flooding within the new site. It will also provide all the necessary actions needed in the control of flooding within this area of study so that a suitable location for dam, reservoirs will be recommended. Finally, GIS approach will be used in the cost of this research work, to help in the control of disasters, erosion, irrigations and flow of water. Key words: GIS, DEM,HRU,BMP
INTRODUCTION Sustainable development requires coordinated, comprehensive and sustained Earth observations for early warning, informed policies and effective decision making. In support of this objective, I intend to put an effort in conducting a study leading a GIS approach to solve the environmental problem of the research site. It is foreseen that these problems of future planning and the derived Products will be distributed via Geoqinetiq Geomatics Gold Medal And Prize Advisory Board Cast to a broad range of user communities. Therefore, an analysis of the Adamawa University new site watershed, on the southern part of mubi in Adamawa state (fig. 1), was conducted by the student of surveying and geoinformatics in 2009-2010. The analysis was initiated to better understanding of the precise mapping project (GPS field campaign, georeferencing and on-screen digitization of analog topographical map at the scale of 1:50,000, and a better documentation of the data for the benefit of the state and the nation as a whole) was also done. Some selected ecosystem components within the watershed was also examine. The purpose of this report is to present report on “what is not know� that was prepared for Geoqinetiq Geomatics Gold Medal And Prize Advisory Board as analysis report. The watershed module report is organized around the key questions for the watershed issues that were developed through field survey, GIS and remote sensing by the researcher. The project site formally belongs to the milk industry known as (Gidan Madara) along Sahuda Road, but after the breakdown of the industry, the site remains vacant for more than a decade. During the Boni Haruna regime In 2002, the state university was established which led to the cancelling, collection and conversion of the Shuware Government Collage into its site. But due to the rapid increase in the population of both staffs and student, brings about the demand for a new site (Sahuda road campus) from the state government and this demand was a success.
LITERATURE REVIEW Over the years, many models have been developed to help agencies assess and control the quality of many nation’s water bodies such as USA, UK e.t.c. Water quality simulation models have been developed by government agencies, academic institutions, and consulting firms. Because end-of-pipe point sources are largely controlled and are highly regulated, more and more focus is being placed on non-point sources which make up a significant portion of pollution in natural waters. There are a large group of non-point source models that have been developed to address water quality concerns. These models are written in standard FORTRAN77 and are executable in the MS-DOS environment. Some of these models have been updated to include a Windows user interface. One of the potential drawbacks to using these models can be the need for very large input data sets. Conversely, spatial averaging can be assumed to decrease the amount of required input data at the potential expense of output accuracy. Some detail on these models is presented briefly. Geographic Information Systems are becoming more useful in modeling water quality because they can incorporate spatially varying data. There are many instances where GIS have been incorporated into modeling efforts, and two basic ways that they have been used are: (1) as a method for deriving input for external models, and (2) as a stand-alone model. Since water quality is integrally related to water quantity, some hydrology models will also be mentioned in the review.
PHOTOGRAPHS ON SITE
Some of the hardware/software Used are listed below:
24 Channel GPS receiver ( 5800) Leveling instruments Total station (TPS 400) Laptop (HP Compaq 6720s) Scanner (HP 3220) Software ArcView 3.2 Ilwist 3.1 Global mapper 11.0 Surfer 8 AutoCad 2009
STUDY AREA The study area is located in Mubi south local Government area, with three conical hills inside, the site is adjacent to the road to Cameron and it experiences a lot of smugglers along its site. Mubi lies at an approximate latitude and longitude
’ ’’ and
’ ’’ respective y with an approximate
population of 225705 (GeoNames geographic database). The area covered by this study is 6494.2015Sqkm of land.
Fig 1. Map of Mubi Showing The Study Area.
TOPOGRAPHICAL ANALYSIS In this study, a topographical analysis was carried out to shows or tells the distribution of details (both natural and man-made features) on the surface of the earth within the study area. It gives information relating to the height of points below or above the mean sea level. Fig. 2 shows the topographical map of the project area; this map shows the distribution of details such as the man-made features (buildings, roads e.t.c.) and natural features (trees, stream, foot paths e.t.c.). It also shows the generated contours at 1meter interval within the project area. The contour ranges from592-666m.
Fig. 2 Topographical map
METHODOLOGY Input data were composed of derived digitization and simplification methods specific to GIS technique. All the vector data (elevation values from on screen digitization and field data) were combined with raster (ortorectified imagery) and correlated, finally analyzing the derived geomorphologic parameters (figure no. 3). The geomorphologic parameters (slope, aspect, elevation, curvature of terrain and roughness) were analyzed individually and put together in a formula, returning the risk of Water flow.. R av = (S + Ex + Al + Fx) * Rg
Digital Elevation Model A digital terrain model (DTM) , also known as a digital surface model (DSM) or digital elevation model (DEM) is a topographic mode of the “bare earth�. All features such as vegetation, buildings, bridges etc. are removed to create the bare earth/ DTM. For the creation of a DEM of the area under examination, 491 x-y-z vector points data, taken from the field, the topographical map was scanned and converted to raster images using ILWIST 3.1 Academic software and the satellite image of the Area was also acquired. An example of x-y-z point data and generated DEM is given in Figure 4.
Figure 4. DEM
Extraction of river network From the accumulated drainage area map the river network can automatically be extracted. a constant drainage area threshold a was used for this purpose. Every cell that has a > a was defined as a river t
t
cell. As can be seen in slope/aspect map in Figure 7, the extracted river Network depends from the chosen drainage area threshold a . The smaller you choose a the more branched is the river network. t
t,
The bigger you choose the threshold value the less branched is your river network because fewer cells are larger than the threshold used to define river cells.
Fig. 5 DEM SHOWING TERRAIN ROUGHNESS
VECTOR MAP The vector map of the study area was generated using the Surfer 8 software to show direction and magnitude of data at points on a map, this vector map shows the natural flood direction within the study area and it was overlay on the terrain roughness. You can create vector maps from information in one grid or two separate grids. The two components of the vector map, direction and magnitude, was automatically generated from a single grid by computing the gradient of the represented surface. At any given grid node, the direction of the arrow points in the direction of the steepest descent. The magnitude of the arrow changes depending on the steepness of the descent. Two-grid vector maps use two separate grid files to determine the vector direction and magnitude. The grids can contain Cartesian or polar data. With Cartesian data, one grid consists of X component data and the other grid consists of Y component data. The Overlay of vector maps on 3D surface maps was done to enhance the presentation.
Reference Vectors 0.00054725744701830.27579776067613
Fig. 6 vector map on DTM
TERRAIN PARAMETERS Slope is between one of the most important geomorphometric parameters of terrain surface, representing an important role in determining the geomorphologic processes that affect a certain area. It represents the quantitative measure of maximal change of elevation values (Shary et. al., 2002), ranging from 0째 to 90째. Base on the DEM of the study area, it can be seen that it is flowing towards the NE, i.e to the blue Zone. Geometrically, slope describes the angle between the horizontal plane and the tangential to the surface and slope is expressed as follows:
Slope gradient can be expressed in either degrees or radians, but more commonly Percentages are used to refer to slope values (tan (S) *100).
Fig7. Slope map (Left) in Ilwist 3.1 and Aspect map (Right) in Arcview 3.2 A survey of water available for runoff of a single storm would consist of measurements to compute water available for runoff at several different sites that vary with respect to altitude, vegetation type, or aspect direction. The erosion pack low-water equivalent would be measured before and after the storm, as would the amount of water from the higher surface or bare soil (lower) surface during the storm. Total storm water available for runoff at each site was then computed from an equation for the site water balance. An equation for the water balance is
where WA is the total water available for runoff R for the storm, in meters; P is the quantity of water from higher that is input to the high or low soil surface during the storm, in meter; ΔSW is the change of higher part water E equivalent during of the storm, in meter; and E is the total evaporative loss during the storm, in. meter; Another parameter is represented by aspect which represents a crucial role in a number of morphological, hydrological and ecological processes. It is defined as the compass direction to which a slope faces, measured in degrees from North in a clockwise direction and ranging from 0° to 360°. Aspect can be defined as (Shary et.al., 2002):
As seen in figure no. 6, the west, North-West and North-East versants are the most representative due to the fact that the rapid downhill flow of a large amount of water risk is higher in those areas.
IMAGES As basic image layer for the terrain model, orthoimages with 6.91×6.96 m image resolution of the study area was taken from the internet using the Google earth 5.3 software. The images were georeferenced in both Global Mapper 11.0 and Ilwist 3.1 software presented in Figure 7 below. The map on the right blow shows the contour of the study area being overlaid on the satellite image, the blue portion of the map indicates the recommended site for future DAM construction generated Arcview.
Fig7. Recommended dam site (Left) in Arcview 3.2 and boundary on image (Right) in Global Mapper v.11
PROFILE Profile curvature is the curvature of a line formed by the intersection of a fictional vertical plane with the ground surface. While a zero value of profile curvature indicates a flat surface, negative values indicate that the surface is upwardly concave and positive values indicate that the surface is upwardly convex. Profile curvature can be determined using the following calculation formula (Evans 1972, quoted by Shary et. al., 2002):
Nonetheless landform is very useful for Water flow risk because it determines the possible water accumulation area or the possible areas of propagation. The concave areas are mostly represented by the bed’s rivers. The convex one’s in genera are represented by the highest s ope va ues. The profile along the major flow channel was generated with the Global Mapper 11.0 so as to graphically visualize the terrain within the valley or concave areas of the site as shown fig 8 below.
Fig. 8 Profile along the steeply area from DEM
Geology and Soils The geology of the watershed affects hydrologic responses in the watershed insofar as it controls bed surface slopes and gradients in stream channels and as it affects substrate materials that control or mediate subsurface flow. Ridges within the North, Middle and South sub watersheds are composed of rocks of sedimentary origin, such as sandstone and shale (Tabor and Cady, 1978). The sides of the ridges are very steep. As a result, the hydrologic response to storms of many smaller, steep-gradient tributaries is prompt.
HYDROLOGICAL RESPONSE UNITS (HRU) Definition For rainfall-runoff modeling the watershed may be divided into areas that have a similar hydrological response, that is based on their physical characteristics (such as soil type, vegetation, slope, etc.) they may have a similar response to a unit input of rainfall. This is the theory behind defining HRUs, i.e. hydrological response units. In this part of the study, HRUs for the new site was defined.
Steps in defining HRUs Since the new site is in a steep Alpine environment, I expect that slope may play an important role in runoff production. For this reason slope, aspect and overlays was used as the primary factor and the proposed land use design as the secondary factor for HRU definition. 3 different slope category groups were determined using the arcview 3.2: 1. Highs slope between (33.728 - 37.944) 째 2. Medium slopes between (16.864 - 21.08) 째 3. Lower slopes (0 - 4.216) 째 Category group 2 subdivided in 9 land use category groups: Residential, recreational, student res, commercial, Green, academic, parking, administrative and others This division resulted in 9 HRUs of land use which are show in Figure 9.
Fig 9 Land Use Map Of The Study Area
The main properties are listed in Table below. S/NO USES Area(m2) 1 residential 1908232 2 recreational 824383.8 3 student res 659122.1 4 commercial 403703.1 5 Green 448696.1 6 academic 1082357 7 parking 51628.61 8 administrative 61575.22 9 others 1051491
total
6491190
The reason why I took the slope as primary factor is, that I think it is a major parameter for runoff modeling and we just want to use these HRU therefore. Further, the subdivision by land use seemed to be possible for me because of the obvious influence on runoff.
TABLE OF DATA The table below will show the field vector data obtained with both 24 channel GPS and TPS 400 Total Station instrument.
KEY HYDROLOGY ISSUES AND KEY QUESTIONS A. Maintaining flows in the Study area and its tributaries that are, to the degree possible, beneficial to human uses and that promote maintenance or restoration of critical ecosystem functions; and B. Effects of management on wetland form and function. These issues were addressed through a key-question process, which is the principal vehicle prescribed by GIS Applications and Guide for advancing through watershed analysis. The key questions are: 1. What are the natural, physical, and biological features of the watershed that control hydrologic responses? 2. What is known about current stream flow characteristics, including peak and low flows? 3. What evidence exists that forest harvesting and road construction have altered frequency and magnitude of peak and low flows? 4. What is currently known about the distribution and extent of wetlands, and what have been the impacts of land management activities on wetlands? 5. How might existing hydrologic monitoring be maintained or augmented to help detect future hydrologic change, to preserve critical ecosystem functions, and to protect public and private property? The key questions were researched using the scientific literature, a brief field investigation, and hydrologic, climatic, and resource mapping databases created and maintained by the researcher. RESPONSES TO KEY QUESTIONS For this report, hydrologic response is defined as a change in a hydrologic variable as a result of changes in rates at which water is added to or taken away from a hydrologic system. Hydrologic variables include stream flow, overland flow rate, water yield, stream and lake stage, hydraulic head, hydraulic gradient, ground-water recharge and discharge, evaporation, transpiration, ground-water flow rate, and soil water content.
Climate Variations of weather and climate are probably the most important determinants of hydrologic responses in most watersheds. Weather refers to meteorological conditions, such as precipitation or air temperature, as they occur at any given instant, and climate refers to the average weather conditions or to recurrent seasonal weather variations during some number of years Vegetation performs a number of functions that can influence hydrologic responses. First, terrestrial vegetation mediates the exchange of water and energy between the atmosphere and the soil and thereby exerts control on the amount of water that is stored in the soil and available to recharge streams or ground water. For example, vascular plants can absorb water from the soil through their roots and transport it to their leaves, where the receipt of energy from the atmosphere causes the water to evaporate. The nature of the leaf surface, such as how efficiently it absorbs down welling solar radiation, in part determines the magnitude of evaporation and, ultimately, the amount of water withdrawn from the soil. During rainfall, some of the precipitation is intercepted and stored on the surfaces of the vegetation. Some of the intercepted water can drip from the vegetation to the soil, and some of the water evaporates into the atmosphere. The process by which water evaporates from wetted vegetation is termed "interception loss." In some situations, the
presence of vegetation can lead to increased inputs of water to the soil surface. Vegetation can intercept some of the moisture from fog and some of that intercepted moisture can drip onto the soil surface.
RESULTS Finally, all the geomorphologic parameters were analyzed together. The study area (650 hectares) was divided in 450 cells with a resolution of 6.91Ă—6.96 meters. Every cell risk coefficient was independently obtained by entering the specific parameters of that area in the final formula. A class of values of Risk of avalanche was established. Finally, for each cell I obtained values varying from 0 to 12.71.
Summary This study and model do provide an effective, scientifically based management tool despite the limitations of the model and the need for more data. The current model calculates flowed based on acquired field data. Loads from individual watersheds were quantified, and the effects of various BMP implementation strategies were examined to help focus those efforts. This tool allows managers, planner, Architecture, surveyors and engineers to quantify load contribution, not only on a subwatershed basis, but also on a land use basis within sub-watersheds. The decision support system developed in this project is merely a starting point. It is intended to be a living model. It provides a framework for developing a more detailed tool to be used by managers and stakeholders in the Adamawa state new site watershed. As monitoring and data collection continues, the model can be updated to allow for more specificity and detail in the analysis. This model refinement will not happen overnight, but as more data becomes available, it can be used to provide more focused guidance for resource managers.
CONCLUSIONS This study demonstrates that GIS is an effective platform for modeling water Quantity and quality in the Adamawa state new site watershed and for developing a decision support system for resource managers. Loadings from the basin sub-watersheds are segregated and attributed to various land uses are described. The experiment was tested and the results confirmed the risk of water flowed to be present in most of the land uses due to the nature of the terrain .The final results were compared with the background from the “terrain� the vector and the raster data confirmed the potential areas which were in a 90 % accurate. The current mapping project could represent a base for land planning and utilization, a method for prevention, maybe a future interactive web mapping, a useful tool for the Management of risk sites and can be applied in different areas and has an educational goal.
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