Environmental Engineering
G.R. Puno; R.C.C. Puno; I.V. Maghuyop
Abstract
BACKGROUND AND OBJECTIVES: Fine topographic information is a key input parameter for a detailed flood simulation and mapping. This study aimed to compare the accuracy statistics of the flood models developed using the digital elevation datasets with different resolutions from the light detection and ...
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BACKGROUND AND OBJECTIVES: Fine topographic information is a key input parameter for a detailed flood simulation and mapping. This study aimed to compare the accuracy statistics of the flood models developed using the digital elevation datasets with different resolutions from the light detection and ranging and interferometric synthetic aperture radar systems.METHODS: The study applied the Hydrologic Engineering Center-Hydrologic Modeling System and Hydrologic Engineering Center-River Analysis System models workable within the geographic information system to simulate and map flood hazards in Maapag Watershed. The models’ validity and accuracy were tested using the confusion error matrix, f-measurement, and the root means square error statistics.FINDINGS: Results show that using the light detection and ranging dataset, the model is accurate at 88%, 0.61, and 0.41; while using the interferometric synthetic aperture radar dataset, the model is accurate at 76%, 0.34, 0.53; for the error matrix, f-measurement, and root mean square error; respectively.CONCLUSION: The model developed using the light detection and ranging dataset showed higher accuracy than the model developed using the interferometric synthetic aperture radar. Nevertheless, the latter can be used for flood simulation and mapping as an alternative to the former considering the cost of model implementation and the smaller degree of accuracy residual error. Hence, flood modelers particularly from local authorities prefer to use coarser datasets to optimize the budget for flood simulation and mapping undertakings.
Environmental Management
G. R. Puno; R. C. Puno; I. V. Maghuyop
Abstract
BACKGROUND AND OBJECTIVES: The study involved developing a two-dimensional flood model to analyze the risk exposure of land use/land cover based on the generated flood hazard maps for the six return period scenarios in the Solana watershed.METHODS: The approach consisted of applying hydrologic and hydraulic ...
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BACKGROUND AND OBJECTIVES: The study involved developing a two-dimensional flood model to analyze the risk exposure of land use/land cover based on the generated flood hazard maps for the six return period scenarios in the Solana watershed.METHODS: The approach consisted of applying hydrologic and hydraulic numerical flood models and the suite of advanced geographic information systems and remote sensing technologies. The process involved utilizing a high-resolution digital elevation model and a set of high-precision instruments such as the real-time kinematic-global position system receiver, digital flow meter, deep gauge, and automatic weather station in collecting the respective data on bathymetry, river discharge, river depth, and rainfall intensity during a particular climatic event, needed for the model development, calibration and validation.FINDINGS: The developed two-dimensional flood model could simulate flood hazard with an 86% accuracy level based on the coefficient of determination statistics. The flood risk exposure analysis revealed that coconut is the most affected, with 31.3% and 37.1% being at risk across the 2-year and 100-year return period scenarios, respectively. Results also showed that rice and pineapple are at risk of flooding damage with the increasing rate of exposure by a magnitude of 42.9 and 9.3 across the 2-year and 100-year flood scenarios, respectively.CONCLUSION: The study highlighted the integration of the findings and recommendations in the localized comprehensive land use plan and implementation to realize the challenge of building a climate change proof and a flood-resilient human settlement in the urbanizing watershed of Solana.
Environmental Engineering
G.R. Puno; R.A. Marin; R.C.C. Puno; A.G. Toledo-Bruno
Abstract
BACKGROUND AND OBJECTIVES: The study explored the capability of the geographic information system interface for the water erosion prediction project, a process-based model, to predict and visualize the specific location of soil erosion and sediment yield from the agricultural watershed of Taganibong.METHODS: ...
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BACKGROUND AND OBJECTIVES: The study explored the capability of the geographic information system interface for the water erosion prediction project, a process-based model, to predict and visualize the specific location of soil erosion and sediment yield from the agricultural watershed of Taganibong.METHODS: The method involved the preparation of the four input files corresponding to climate, slope, land management, and soil properties. Climate file processing was through the use of a breakpoint climate data generator. The team had calibrated and validated the model using the observed data from the three monitoring sites.FINDINGS: Model evaluation showed a statistically acceptable performance with coefficient of determination values of 0.64 (probability value = 0.042), 0.85 (probability value = 0.000), and 0.69 (probability value = 0.001) at 95% level, for monitoring sites 1, 2, and 3, respectively. A further test revealed a statistically satisfactory model performance with root mean square error-observations standard deviation ratio, Nash-Sutcliffe efficiency, and percent bias of 0.62, 0.61, and 44.30, respectively, for monitoring site 1; 0.65, 0.56, and 25.60, respectively, for monitoring site 2; and 0.60, 0.65, and 27.90, respectively, for monitoring site 3. At a watershed scale, the model predicted the erosion and sediment yield at 89 tons per hectare per year and 22 tons per hectare per year, respectively, which are far beyond the erosion tolerance of 10 tons per hectare per year. The sediment delivery ratio of 0.20 accounts for a total of 126,390 tons of sediments that accumulated downstream in a year.CONCLUSION: The model generated maps that visualize a site-specific hillslope, which is the source of erosion and sedimentation. The study enables the researchers to provide information helpful in the formulation of a sound policy statement for sustainable soil management in the agricultural watershed of Taganibong.
G.R. Puno; R.C.C. Puno
Abstract
Geomorphometric features and land use/land cover are essential in the context of watershed prioritization for resources conservation and protection. Watersheds in tropical regions like the Philippines are under threat of degradation due to the combined effects of uncontrolled agricultural activities ...
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Geomorphometric features and land use/land cover are essential in the context of watershed prioritization for resources conservation and protection. Watersheds in tropical regions like the Philippines are under threat of degradation due to the combined effects of uncontrolled agricultural activities in the uplands and frequently increasing erosive precipitations brought about by climate change. Watershed managers are challenged with these pressing issues and concerns because most watersheds have no sufficient data as a basis for decision making. This paper presents the method of analyzing the different geomorphometric features and the existing land use or land cover to assess the propensity of the watershed against erosion so that areas needing immediate treatment can be prioritized. Arbitrarily, fourteen subwatersheds coded as SW1 to SW14 were delineated using a digital elevation model and geographic information system tool. Geomorphometric features categorized as areal aspect, relief features, and channel morphology parameters were generated and analyzed. Parameters having direct and inverse effect to erosion risk was used as the criteria in the ranking process. Land use/land cover was added to geomorphometric parameters to come up with compound values for final prioritization. Results showed that SW13, SW14, and SW4 were classified under very high priority implying focus for appropriate management actions while SW10, SW6, and SW7 were classified under very low priority suggesting favorable environmental condition in these areas. The study provides significant information helpful to watershed managers and planners especially in crafting a plan for integrated watershed management wherein programs and projects implementation have to be prioritized.
Environmental Management
B.A.M. Talisay; G.R. Puno; R.A.L. Amper
Abstract
Flooding is one of the most occurring natural hazards every year risking the lives and properties of the affected communities, especially in Philippine context. To visualize the extent and mitigate the impacts of flood hazard in Malingon River in Valencia City, Bukidnon, this paper presents the combination ...
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Flooding is one of the most occurring natural hazards every year risking the lives and properties of the affected communities, especially in Philippine context. To visualize the extent and mitigate the impacts of flood hazard in Malingon River in Valencia City, Bukidnon, this paper presents the combination of Geographic Information System, high-resolution Digital Elevation Model, land cover, soil, observed hydro-meteorological data; and the combined Hydrologic Engineering Center-Hydrologic Modeling System and River Analysis System models. The hydrologic model determines the precipitation-runoff relationships of the watershed and the hydraulic model calculates the flood depth and flow pattern in the floodplain area. The overall performance of hydrologic model during calibration was “very good fit” based on the criterion of Nash-Sutcliffe Coefficient of Model Efficiency, Percentage Bias and Root Mean Square Error – Observations Standard Deviation Ratio with the values of 0.87, -8.62 and 0.46, respectively. On the other hand, the performance of hydraulic model during error computation was “intermediate fit” using F measure analysis with a value of 0.56, using confusion matrix with 80.5% accuracy and the Root Mean Square Error of 0.47 meters. Flood hazard maps in 2, 5, 10, 25, 50 and 100-year return periods were generated as well as the number of flooded buildings in each flood hazard level and in different return periods were determined. The output of the study served as an important basis for a more informed decision and science-based recommendations in formulating local and regional policies for more effective and cost-efficient strategies relative to flood hazards.
R.A.L. Amper; G.R. Puno; R.C.C. Puno
Abstract
Some riparian areas of the country are in danger of deterioration due to uncontrolled exploitation coupled with loose implementation of environmental protection policies and regulations. Muleta River, a major watershed in Bukidnon, Philippines, was assessed to determine the present condition of its riparian ...
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Some riparian areas of the country are in danger of deterioration due to uncontrolled exploitation coupled with loose implementation of environmental protection policies and regulations. Muleta River, a major watershed in Bukidnon, Philippines, was assessed to determine the present condition of its riparian habitat. Abiotic and biotic conditions of the river were assessed. Other factors including land cover, population density, and river geomorphologic characteristics contributing to the river condition were also evaluated. Results revealed that Muleta Watershed is in sub-optimal condition signifying favorable condition for floral and faunal habitat. However, considerable degradation in some isolated cases was likewise spotted. Biotic condition has shown greater degradation approaching marginal condition compared to the abiotic condition which is yet in the upper sub-optimal condition. It was found out that the midstream portion of the watershed is the most disturbed, followed by the downstream area and lastly by the upstream portion. The extent of agricultural cultivation is found as one of the significant factors affecting the health of the riparian habitat areas. It is recommended that riparian protection policies must be formulated and implemented to abate, if not prevent, the impact of anthropogenic interventions resulting to overexploitation in the riparian areas especially in midstream portion of the river.
R.C.C. Puno; G.R. Puno; B.A.M. Talisay
Abstract
Predicting the impact of land cover and climate change on hydrologic responses using modeling tools are essential in understanding the movement and pattern of hydrologic processes within the watershed. The paper provided potential implications of land conversions and climate change scenarios on the hydrologic ...
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Predicting the impact of land cover and climate change on hydrologic responses using modeling tools are essential in understanding the movement and pattern of hydrologic processes within the watershed. The paper provided potential implications of land conversions and climate change scenarios on the hydrologic processes of Muleta watershed using soil and water assessment tool model. Model inputs used include interferometric synthetic aperture radar-digital elevation model, 2016 land cover map, soil map, meteorological and hydrologic data. The model was calibrated using appropriate statistical parameters (R2=0.80, NS=0.80 and RSR=0.45). Model validation using observed streamflow with the same statistical parameters (R2 = 0.79, NS = 0.67 and RSR = 0.57) showed that the result was statistically acceptable. The model provided potential implications of land conversions and climate change adversely affecting hydrologic processes of critical watersheds. Climate change projections with a 13% decrease in rainfall directly influenced the decrease in hydrologic processes. Meanwhile, urbanization had influenced the increase in surface runoff, evapotranspiration, and baseflow. The increase of forest vegetation resulted in a minimal decrease in baseflow and surface runoff. The watershed hydrologic processes were influenced by changes in land cover and climate. Results of this study are useful by the localities and policy makers in coming up with a more informed decision relative to the issues and concern on hydrological responses in the uplands.
