scholarly journals A Model-Based Tool for Assessing the Impact of Land Use Change Scenarios on Flood Risk in Small-Scale River Systems—Part 2: Scenario-Based Flood Characteristics for the Planned State of Land Use

Hydrology ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 130 ◽  
Author(s):  
Frauke Kachholz ◽  
Jannik Schilling ◽  
Jens Tränckner

Land use changes can significantly influence the water balance, and thus especially the development of flood-triggering runoff peaks. Hence, it is advisable to assess possible changes already at the level of municipal planning. Since many different actors are usually involved in spatial planning, it is useful to provide a shared platform where stakeholders can access the same information to analyze and evaluate flood hazards. Therefore, a GIS routine for the prediction of soil sealing induced runoff peaks and resulting potential flooding in the watercourse was developed, which is embedded in a GIS based decision support system (GIS-DSS). The so-called storm water routine (SWR) is founded on preprocessed flood characteristics, calculated by means of hydrological/hydraulic models (described in part 1). The potential impact of land use change is assessed purely in GIS as flow difference which is routed through the river system. To validate this simplified method, a process model was set up with an exemplary land use change and its results were compared with the GIS-based results. For 16 of the 18 rainfall scenarios tested, the SWR provided very good to good agreement with the detailed model. For short and highly dynamic rain events the SWR approach is less reliable. Several supplements like the integration of LID are conceivable.

Hydrology ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 102
Author(s):  
Frauke Kachholz ◽  
Jens Tränckner

Land use changes influence the water balance and often increase surface runoff. The resulting impacts on river flow, water level, and flood should be identified beforehand in the phase of spatial planning. In two consecutive papers, we develop a model-based decision support system for quantifying the hydrological and stream hydraulic impacts of land use changes. Part 1 presents the semi-automatic set-up of physically based hydrological and hydraulic models on the basis of geodata analysis for the current state. Appropriate hydrological model parameters for ungauged catchments are derived by a transfer from a calibrated model. In the regarded lowland river basins, parameters of surface and groundwater inflow turned out to be particularly important. While the calibration delivers very good to good model results for flow (Evol =2.4%, R = 0.84, NSE = 0.84), the model performance is good to satisfactory (Evol = −9.6%, R = 0.88, NSE = 0.59) in a different river system parametrized with the transfer procedure. After transferring the concept to a larger area with various small rivers, the current state is analyzed by running simulations based on statistical rainfall scenarios. Results include watercourse section-specific capacities and excess volumes in case of flooding. The developed approach can relatively quickly generate physically reliable and spatially high-resolution results. Part 2 builds on the data generated in part 1 and presents the subsequent approach to assess hydrologic/hydrodynamic impacts of potential land use changes.


Hydrology ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 17 ◽  
Author(s):  
Sekela Twisa ◽  
Shija Kazumba ◽  
Mathew Kurian ◽  
Manfred F. Buchroithner

Understanding the variation in the hydrological response of a basin associated with land use changes is essential for developing management strategies for water resources. The impact of hydrological changes caused by expected land use changes may be severe for the Wami river system, given its role as a crucial area for water, providing food and livelihoods. The objective of this study is to examine the influence of land use changes on various elements of the hydrological processes of the basin. Hybrid classification, which includes unsupervised and supervised classification techniques, is used to process the images (2000 and 2016), while CA–Markov chain analysis is used to forecast and simulate the 2032 land use state. In the current study, a combined approach—including a Soil and Water Assessment Tool (SWAT) model and Partial Least Squares Regression (PLSR)—is used to explore the influences of individual land use classes on fluctuations in the hydrological components. From the study, it is evident that land use has changed across the basin since 2000 (which is expected to continue in 2032), as well as that the hydrological effects caused by land use changes were observed. It has been found that the major land use changes that affected hydrology components in the basin were expansion of cultivation land, built-up area and grassland, and decline in natural forests and woodland during the study period. These findings provide baseline information for decision-makers and stakeholders concerning land and water resources for better planning and management decisions in the basin resources’ use.


Proceedings ◽  
2020 ◽  
Vol 30 (1) ◽  
pp. 62
Author(s):  
Zahra Kalantari ◽  
Johanna Sörensen

The densification of urban areas has raised concerns over increased pluvial flooding. Flood risk in urban areas might increase under the impact of land use changes. Urbanisation involves the conversion of natural areas to impermeable areas, causing lower infiltration rates and increased runoff. When high-intensity rainfall exceeds the capacity of an urban drainage system, the runoff causes pluvial flooding in low-laying areas. In the present study, a long time series (i.e., 20 years) of geo-referenced flood claims from property owners has been collected and analysed in detail to assess flood risk as it relates to land use changes in urban areas. The flood claim data come from property owners with flood insurance that covers property loss from overland flooding, groundwater intrusion through basement walls, as well as flooding from drainage systems; these data serve as a proxy of flood severity. The spatial relationships between land use change and flood occurrences in different urban areas were analysed. Special emphasis was placed on examining how nature-based solutions and blue-green infrastructure relate to flood risk. The relationships are defined by a statistical method explaining the tendencies whereby land use change affects flood risk.


2013 ◽  
Vol 10 (10) ◽  
pp. 6323-6337 ◽  
Author(s):  
S. J. Smith ◽  
A. Rothwell

Abstract. We examine historical and future land-use emissions using a simple mechanistic carbon-cycle model with regional and ecosystem specific parameterizations. We use the latest gridded data for historical and future land-use changes, which includes estimates for the impact of forest harvesting and secondary forest regrowth. Our central estimate of net terrestrial land-use change emissions, exclusive of climate–carbon feedbacks, is 250 GtC over the last 300 yr. This estimate is most sensitive to assumptions for preindustrial forest and soil carbon densities. We also find that land-use change emissions estimates are sensitive to the treatment of crop and pasture lands. These sensitivities also translate into differences in future terrestrial uptake in the RCP (representative concentration pathway) 4.5 land-use scenario. The estimate of future uptake obtained here is smaller than the native values from the GCAM (Global Change Assessment Model) integrated assessment model result due to lower net reforestation in the RCP4.5 gridded land-use data product.


2019 ◽  
Vol 11 (3) ◽  
pp. 696 ◽  
Author(s):  
Qun Liu ◽  
Zhaoping Yang ◽  
Cuirong Wang ◽  
Fang Han

In this study, we analyzed the temporal-spatial variations of the characteristics of land use change in central Asia over the past two decades. This was conducted using four indicators (change rate, equilibrium extent, dynamic index, and transfer direction) and a multi-scale correlation analysis method, which explained the impact of recent environmental transformations on land use changes. The results indicated that the integrated dynamic degree of land use increased by 2.2% from 1995 to 2015. The areas of cropland, water bodies, and artificial land increased, with rates of 1047 km2/a, 39 km2/a, and 129 km2/a, respectively. On the other hand, the areas of forest, grassland, and unused land decreased, with rates of 54 km2/a, 803 km2/a, and 359 km2/a, respectively. There were significant increases in cropland and water bodies from 1995 to 2005, while the amount of artificial land significantly increased from 2005 to 2015. The increased areas of cropland in Xinjiang were mainly converted from grassland and unused land from 1995 to 2015, while the artificial land increase was mainly a result of the conversion from cropland, grassland, and unused land. The area of cropland rapidly expanded in south Xinjiang, which has led to centroid position to move cropland in Xinjiang in a southwest direction. Economic development and the rapid growth of population size are the main factors responsible for the cropland increases in Xinjiang. Runoff variations have a key impact on cropland changes at the river basin scale, as seen in three typical river basins.


2015 ◽  
Vol 17 (4) ◽  
pp. 870-881 ◽  

<div> <p>In this study, we investigated the separate and combined impacts of climate and land-use changes on hydrological response in the Central Highlands of Vietnam during the period 1981-2009. The Mann-Kendall and Pettit tests were applied to detect the trends in the hydro-meteorological data. The Soil and Water Assessment Tool (SWAT) was setup in the region, and evaluation based on daily data highlights the models adequacy. From this, the responses of hydrology to climate variability and land-use changes were considered. Overall, variability in climate seems to strongly drive the variability in the hydrological response in comparison to alternations in the hydrological regime due to land-use change during the period 1981-2009. The results indicate that land-use change had a minor impact on the annual flow (0.4% reduction), whilst the impact from climate variability had been more significant (13.5% change). Under the impact of coupled climate variability and land-use change, the annual streamflow increased by 13.1%.</p> </div> <p>&nbsp;</p>


2021 ◽  
Vol 325 ◽  
pp. 07001
Author(s):  
Utia Kafafa ◽  
Rika Harini

The National Southern Cross Road Route well known as Jalan Jalur Lintas Selatan (JJLS) in Indonesia. The segment which crosses Bantul Regency has 16.65 km long. The development of JJLS will have various kinds of impacts on the community around the road infrastructure. This study wants to know how the impact of the development that saw from the spatial dynamics of land-use change. The study area is located in Poncosari, Gadingsari, Srigading, Tirtohargo, and Parangtritis Village. We process the data using the map overlay technique then analyze it with quantitative descriptive. The results of this study are the development of JJLS in Bantul Regency has not significantly affected the land-use changes. It is evident from the location of the land-use change which is far from the road and tends to be disheveled. The Land-use changes that occur do not form a specific pattern such as the pattern of conversion of agricultural land into non-agricultural land. The less significant changes in land use are caused by the condition of the JJLS which is not yet fully connected. Moreover, the status of land ownership around JJLS is Sultan Ground so a special permit is needed if the community wants to use the land.


2020 ◽  
Author(s):  
Joris Eekhout ◽  
Carolina Boix-Fayos ◽  
Pedro Pérez-Cutillas ◽  
Joris de Vente

&lt;p&gt;The Mediterranean region has been identified as one of the most affected global hot-spots for climate change. Recent climate change in the Mediterranean can be characterized by faster increasing temperatures than the global mean and significant decreases in annual precipitation. Besides, important land cover changes have occurred, such as reforestation, agricultural intensification, urban expansion and the construction of many reservoirs, mainly with the purpose to store water for irrigation. Here we study the impacts of these changes on several ecosystem services in the Segura River catchment, a typical large Mediterranean catchment where many of the before mentioned changes have occurred in the last half century. We applied a hydrological model, coupled with a soil erosion and sediment transport model, to study the impact of climate and land cover change and reservoir construction on ecosystem services for the period 1971-2010. Eight ecosystem services indicators were defined, which include runoff, plant water stress, hillslope erosion, reservoir sediment yield, sediment concentration, reservoir storage, flood discharge and low flow. To assess larger land use changes, we also applied the model for an extended period (1952-2018) to the Taibilla subcatchment, a typical Mediterranean mountainous subcatchment, which plays an important role in the provision of water within the Segura River catchment. As main results we observed that climate change in the evaluated period is characterized by a decrease in precipitation and an increase in temperature. Detected land use change over the past 50 years is typical for many Mediterranean catchments. Natural vegetation in the headwaters increased due to agricultural land abandonment. Agriculture expanded in the central part of the catchment, which most likely is related to the construction of reservoirs in the same area. The downstream part of the catchment is characterized by urban expansion. While land use changed in more than 30% of the catchment, most impact on ecosystem services can be attributed to climate change and reservoir construction. All these changes have had positive and negative impacts on ecosystem services. The positive impacts include a decrease in hillslope erosion, sediment yield, sediment concentration and flood discharge (-21%, -18%, -82% and -41%, respectively). The negative impacts include an increase in plant water stress (+5%) and a decrease in reservoir storage (-5%). The decrease in low flow caused by land use change was counteracted by an increase in low flow due to reservoir construction. The results of our study highlight how relatively small climate and land use changes compared to the changes foreseen for the coming decades, have had an important impact on ecosystem services over the past 50 years.&lt;/p&gt;


2020 ◽  
Vol 12 (14) ◽  
pp. 5707
Author(s):  
Zhiyin Wang ◽  
Jiansheng Cao ◽  
Chunyu Zhu ◽  
Hui Yang

The development of the Xiong’an New Area is a crucial strategy for the next millennium in China. The ecosystem upstream of the Xiong’an New Area, serving for the development of the Xiong’an New Area, changed with land use changes. To analyze the contribution rate of the land use change to the ecosystem service value, we analyzed the land use changes of three small watersheds (7318.56 km2) upstream of the Xiong’an New Area based on a total of six phases of land use data from 1980 to 2015. Then, the ecosystem service value (ESV) was calculated using the equivalent factor method. The results showed that the construction land and arable land were the largest land use types that increased and decreased in the area of the study area, respectively. The grassland and construction land were the land use types with the largest transfer-out area and transfer-in area, respectively. The regulating services accounted for the largest proportion of total ESV among different ecosystem service functions, and the grassland and woodland accounted for the largest proportion of total ESV among different land use types. ESV in the study area fluctuated slightly from 1980 to 2015. The decrease of ESV mainly occurred in the surrounding areas of mountain towns, and the conversion of cultivated land to construction land was the main reason for the decrease of ESV in this area. The conversion of grassland to construction land had the largest contribution rate to the decrease of ESV in the study area, while the conversion of grassland to waters had the largest contribution rate to the increase of ESV. In conclusion, controlling the development of construction land and strengthening water resources’ protection may improve the ecosystem service value in the upstream Xiong’an New Area in the future.


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