quaternary Article Approach for Analysis of Land-Cover Changes and Their Impact on Flooding Regime Badri Bhakta Shrestha Department of Civil Engineering, The University of Tokyo, Tokyo 113-8654, Japan; [email protected] or [email protected] Received: 6 June 2019; Accepted: 26 July 2019; Published: 28 July 2019 Abstract: This study focused on the analysis of land-use/land-cover changes and their impact on flood runoff, flood hazards and inundation, focusing in the Pampanga River basin of the Philippines. The land-cover maps for the years 1996 and 2016 were generated using Landsat images, and the land cover changes were analyzed using TerrSet Geospatial Monitoring and Modeling System (TGMMS). Based on an empirical approach and considering variable factors, the land-cover maps for the future were predicted using Land Change Modeler (LCM). After preparation of land-cover maps for past and future years, flood characteristics were analyzed using a distributed hydrological model named the rainfall runoff inundation (RRI) model with a land-cover map for different years. The impacts of land cover changes on flood runoff, flood volume and flood inundation were analyzed for 50- and 100-year floods. The results show that flood runoff, flood inundation volume and flood extent areas may increase in the future due to land-cover change in the basin. Keywords: land cover change; machine learning; Landsat images; GIS; flood hazard; rainfall-runoff-inundation 1. Introduction Many places in the world are hotspots of risk from extreme weather-related events; and disaster risk are likely to increase due to a combination of land-use/land-cover changes, population growth, climate change, and development activities [1]. Flood risk, climate change and social change have increasingly become a global concern, and also, vulnerabilities related to land use change and climate change have, potentially, a very strong effect on catchment hydrology, floods and damages. Based on previous literature, Blöschl et al. [2] hypothesized the impact of climate and land-use/land-cover changes on hydrological response as a function of catchment scale as shown in Figure1, which shows that sudden changes in the watershed response can occur due to land use/land cover change [3]. The impact of climate change on magnitude and frequency of floods has been widely investigated [4–6]. Similarly, numerous researches focused on study on the impacts of land cover changes on watershed hydrological response [3,7–9], however, only a few of them focused on analyzing the impact of land-cover change in river floods using distributed hydrological modeling [7]. Since the changes in land use/land cover and their spatial distribution have significant impacts on river flow and flooding [7,9], land-cover change analysis and its impact on hydrological processes become the prominent research topics in recent years [8,10]. To analyze such impacts of land-cover changes, it is essential to analyze dynamics of land cover changes, and it is also necessary to investigate hydrological impacts of land use changes using hydrological modeling [7]. The dynamics of land-cover change can be monitored and observed by using remotely sensed satellite-based data [9], and land-cover maps can also be generated by using satellite data such as Landsat images [3,9,11,12] and Moderate Resolution Imaging Spectroradiometer (MODIS) images [13,14]. Quaternary 2019, 2, 27; doi:10.3390/quat2030027 www.mdpi.com/journal/quaternary Quaternary 2019, 2, 27 2 of 18 Quaternary 2019, 2, x 2 of 18 45 ResearchersResearchers have have used used different different approaches approaches to to analyze analyze impacts impacts of of land-cover land-cover changes changes on on flood flood 46 characteristicscharacteristics or or hydrological hydrological response, response, for for example, example, a a Hydrologic Hydrologic Engineering Engineering Centre–Hydrologic Centre–Hydrologic 47 ModelingModeling System System (HEC–HMS) (HEC–HMS) model model [8,10], [8,10], Curve Curve Number Number based based flood flood runoff runoff estimationestimation [3,13], [3,13], 48 distributeddistributed rainfall rainfall runoff runoff modelmodel [7]. [7]. Most Most of of these these studies studies mainly mainly focused focused on on analysis analysis of of impact impact of of 49 land-coverland-cover change change on on river river runoff. runoff .However, However, invest investigationigation of of impact impact of of land land-cover-cover change change on on flood flood 50 inundationinundation are are limited. limited. In In addition, addition, the the management management and and good good planning planning of of land land cover cover can can provide provide 51 anan important important role role in in the the flood flood management, management, climate climate change change adaptation adaptation and and land land degradation degradation [9]; [9]; 52 therefore,therefore, understandingunderstanding impactsimpacts of of land-use land-use and and land-cover land-cover changes changes on flood on runo floodff and runoff inundation and 53 inundationis necessary is for necessary proper managementfor proper management and planning and of landplanning use as of well land as use to reduceas well the as riskto reduce of flood the in 54 riskthe of future. flood Therefore,in the future. it is Theref very importantore, it is very to analyze important land-cover to analyze changes land-cover and their changes impact and on their flood 55 impactrunoff onand flood flood runoff inundation and flood using inundation the rainfall us runoing theff inundation rainfall runoff (RRI) inundation model. (RRI) model. 56 ThisThis study study focused onon analysis analysis of of land-use land-use/land-cover/land-cover changes changes and and their their impact impact on flood on runofloodff , 57 runoff,flood hazardsflood hazards and inundation and inundation in the Pampanga in the RiverPampanga basin ofRiver the Philippines.basin of the The Philippines. land-cover mapsThe 58 land-coverfor past years maps were for generated past years using were Landsat generated images using and Landsat their changes images wereand their also analyzed.changes were Then, also the 59 analyzed.land-cover Then, maps the for land-cover the future weremaps predicted for the future using Landwere Changepredicted Modeler using (LCM).Land Change After preparation Modeler 60 (LCM).of land-cover After preparation maps for past of andland-cover future years,maps floodfor past characteristics and future wereyears, analyzed flood characteristics using a distributed were 61 analyzedhydrological using model, a distributed namely thehydrological RRI model, model, with anamely land-cover the RRI map model, for diff wierentth a years. land-cover The impacts map for of 62 differentland cover years. changes The onimpacts flood runoof landff, flood cover volume changes and on flood flood inundation runoff, wereflood analyzedvolume and for 50- flood and 63 inundation100-year flood were cases. analyzed for 50- and 100-year flood cases. Land use/land cover change Climate variability Impact Catchment Scale 64 Figure 1. Land-use and climate change impact on hydrological response [2,3]. 65 Figure 1. Land-use and climate change impact on hydrological response [2,3]. 2. Study Area 66 2. Study Area The Pampanga River basin, which is located in the Region III (Central Luzon) of the Philippines, 67 is theThe fourth Pampanga largest basinRiver in basin, the Philippines. which is Figurelocated2 showsin the theRegion location III map,(Central basin Luzon) boundary of andthe 68 Philippines,digital elevation is the modelfourth (DEM)largest withbasin elevation in the Ph rangesilippines. ofthe Figure study 2 shows site. The the catchment location map, area basin of the 69 boundarystudy site and is approximately digital elevation 10,645 model km2 (DEM)(based with on digital elevation elevation ranges model of the of study study site. area) The and catchment the length 2 70 areaof the of the main study Pampanga site is approximately River is about 10,645 260 km. km About (based 95% on digital basin areaelevation lies in model Nueva of Ecija,study Tarlac,area) 71 andPampanga, the length and of Bulacan the main provinces Pampanga of theRiver Region is about III, while 260 km. the remainingAbout 95% 5% basin area area is part lies of in the Nueva other 72 Ecija,seven Tarlac, provinces Pampanga, of the Region and Bulacan III such provinces as Aurora, of Zambales, the Region Rizal, III, Quezon,while the Pangasinan, remaining Bataan,5% area and is 73 partNueva of Vizcayathe other [15 seven,16]. Theprovinces average of annual the Region precipitation III such in theas basinAurora, is 2155Zambales, mm [17 Rizal,]. There Quezon, are two 74 Pangasinan,multi-purpose Bataan, dams and in the Nueva basin Vizcaya such as the[15,16]. Pantabangan The average dam annual (storage precipitation capacity of 2966in the million basin mis3 ) 75 2155and mm Angat [17]. dam There (storage are two capacity multi- ofpurpose 850 million dams m 3in). the There basin are such also twoas the swamp Pantabangan areas in thedam river (storage basin 3 3 76 capacitysuch as Candabaof 2966 million (250 km m2) and SanAngat Antonio dam (storage (120 km capacity2)[17]. of 850 million m ). There are also two 2 2 77 swampThe areas population in the river density basin in such the studyas Candaba area in (250 2010 km was) and 630 San persons Antonio/km 2(120and km the) annual[17]. average 2 78 populationThe population growth density rate from in 1980the study to 2010 area was in 2010 about was 2.61%, 630 persons/km [17]. The cropland and the areasannual are average widely 79 population growth rate from 1980 to 2010 was about 2.61%, [17]. The cropland areas are widely 80 spread over the central and downstream parts of the Pampanga River basin which are relatively flat Quaternary 2019, 2, 27 3 of 18 Quaternary 2019, 2, x 3 of 18 Quaternary 2019, 2, x 3 of 18 81 spreadand lowland over the areas, central and and built-up downstream area is scattered parts of thein the Pampanga basin [18].