Natural Water Retention Research Articles

Monitoring Green Infrastructure for Natural Water Retention Using Copernicus Global Land Products

Nature-based solutions are increasingly relevant tools for spatial and environmental planning, climate change adaptation (CCA), and disaster risk reduction (DRR). For this reason, a wide range of institutions, governments, and financial bodies are currently promoting the use of green infrastructure (GI) as an alternative or a complement to traditional grey infrastructure. A considerable amount of research already certifies the benefits and multi-functionality of GI: natural water retention measures (NWRMs), as GIs related specifically to the water sector are also known, are, for instance, a key instrument for the prevention and mitigation of extreme phenomena, such as floods and droughts. However, there are persisting difficulties in locating and identifying GI and one of the most promising solutions to this issue, the use of satellite-based data products, is hampered by a lack of well-grounded knowledge, experiences, and tools. To bridge this gap, we performed a review of the Copernicus Global Land Service (CGLS) products, which consist of freely-available bio-geophysical indices covering the globe at mid-to-low spatial resolutions. Specifically, we focused on vegetation and energy indices, examining previous research works that made use of them and evaluating their current quality, aiming to define their potential for studying GI and especially NWRMs related to agriculture, forest, and hydro-morphology. NWRM benefits are also considered in the analysis, namely: (i) NWRM biophysical impacts (BPs), (ii) ecosystem services delivered by NWRMs (ESs), and (iii) policy objectives (POs) expressed by European Directives that NWRMs can help to achieve. The results of this study are meant to assist GI users in employing CGLS products and ease their decision-making process. Based on previous research experiences and the quality of the currently available versions, this analysis provides useful tools to identify which indices can be used to study several types of NWRMs, assess their benefits, and prioritize the most suitable ones.

Can Land Cover Changes Mitigate Large Floods? A Reflection Based on Partial Least Squares-Path Modeling

Common approaches to large flood management are Natural Water Retention Measures and detention basins. In this study, a Partial Least Squares-Path Model (PLS-PM) was defined to set up a relationship between dam wall heights and biophysical parameters, in critical flood risk zones of continental Portugal. The purpose was to verify if the heights responded to changes in the biophysical variables, and in those cases to forecast landscape changes capable to reduce the heights towards sustainable values (e.g., <8 m). The biophysical parameters comprised a diversity of watershed characteristics, such as land use and geology, surface runoff, climate indicators and the dam heights. The results have shown that terrain slope (w > 0.5), rainfall (w > 0.4) and sedimentary rocks (w > 0.5) are among the most important variables in the model. Changes in these parameters would trigger visible changes in the dam wall height, but they are not easily or rapidly modified by human activity. On the other hand, the parameters forest occupation and runoff coefficient seem to play a less prominent role in the model (w < 0.1), even though they can be significantly modified by human intervention. Consequently, in a scenario of land cover change where forest occupation is increased by 30% and impermeable surfaces are decreased by 30%, interferences in the dam heights were small. These results open a discussion about the feasibility to mitigate large floods using non-structural measures such as reforestation.

Application of Natural Water Retention Measures in Flood Management

Due to climate change, increasingly extreme weather conditions and runoff parameters are leading to the enhancement of flood risk. The increasing probability of fast flowing, high intensity flash floods jeopardize both the residents of small municipalities and the fields of farmers, especially in the downstream areas of mountainous and hilly regions. In many cases the protection of settlements cannot be solved through conventional flood management approaches due to high investment costs and built-in floodplains. The main goal of this article is to analyse the potential of flood risk mitigation with applying natural water retention measures. These additional measures could have a positive effect on the quality and quantity of surface and groundwater. Research results facilitate an even more effective preparation in a way of applying nature based solutions to supplement traditional flood management.

Soft rock for improving crop yield in sandy soil in the Mu Us desert, China

Soft rock efficiently retains water because it is hard when dry but expands rapidly when wet, thus it can be used as a natural water retention agent. Therefore, soft rock can be blended with sandy soil to enhance the water-holding capacity of sandy land. Understanding how soft rock content in sandy soil affects corn growth (Zea mays L.) is essential for enhancing local agricultural production in the Mu Us Desert. The Root Zone Water Quality Model 2 was calibrated and validated based on 2-years of experimental data for composite soils prepared at three ratios of soft rock to sand (1:1, 1:2, and 1:5 v/v), and then used to estimate the water non-limiting potential yield (Yp) and the potential yield of a rainfed crop [Yp(r)], along with yield gap [YG(r)] of corn using the weather data from 1990 to 2013 in the Mu Us Desert. The mean simulated Yp(r) of corn in the compound soil at a ratio of 1:2 was significantly higher than that of the compound soil at 1:1 and 1:5 ratios, respectively. The mean simulated Yp(r)s of corn were 2.551, 3.527, and 2.924 Mg ha−1 and the YG(r)s were 6.071, 5.096, and 5.698 Mg ha−1 for 1:1, 1:2, and 1:5 ratios, respectively. The crop yield depends on the amount of soft rock added to the sandy soils.

The land morphology approach to flood risk mapping: An application to Portugal

In the last decades, the increasing vulnerability of floodplains is linked to societal changes such as population density growth, land use changes, water use patterns, among other factors. Land morphology directly influences surface water flow, transport of sediments, soil genesis, local climate and vegetation distribution. Therefore, the land morphology, the land used and management directly influences flood risks genesis. However, attention is not always given to the underlying geomorphological and ecological processes that influence the dynamic of rivers and their floodplains.Floodplains are considered a part of a larger system called Wet System (WS). The WS includes permanent and temporary streams, water bodies, wetlands and valley bottoms. Valley bottom is a broad concept which comprehends not only floodplains but also flat and concave areas, contiguous to streams, in which slope is less than 5%. This will be addressed through a consistent method based on a land morphology approach that classifies landforms according to their hydrological position in the watershed. This method is based on flat areas (slopes less than 5%), surface curvature and hydrological features.The comparison between WS and flood risk data from the Portuguese Environmental Agency for the main rivers of mainland Portugal showed that in downstream areas of watersheds, valley bottoms are coincident with floodplains modelled by hydrological methods. Mapping WS has a particular interest in analysing river ecosystems position and function in the landscape, from upstream to downstream areas in the watershed. This morphological approach is less demanding data and time-consuming than hydrological methods and can be used as the preliminary delimitation of floodplains and potential flood risk areas in situations where there is no hydrological data available.The results were also compared with the land use/cover map at a national level and detailed in Trancão river basin, located in Lisbon metropolitan area, an urbanized basin that suffered heavy flooding in the last decades. This study also contributes to a better understanding of the basin morphology at a local-scale and the effects of soil sealing in downstream flood risks.This work will contribute to the understanding of the morphology, ecology and land use of watersheds that could be used to reduce runoff and downstream flood risk. This can be accomplished by using natural water retention and infiltration methods or higher-level based planning instead of a reaction to local decisions on flood hazards. This morphological approach to map landforms, including wet system, is a valuable tool to assist policy makers and planners in flood risk and land use management, floodplain restoration, agricultural land management practices, and location of human activities according to ecological suitability.

Urban Water Retention Measures

Many cities and urban areas are located in flood plains because land is fertile and flat which is suitable for agriculture and urban development. Rivers provide water supply for domestic, industrial and irrigation uses; they also provide convenient means for navigation, transportation and communication. Cities have large percentage of impervious areas that prevent effective infiltration of rainfall into soil. To have successful flood control and flood risk management, we should consider not only hydraulic and engineering aspects but also socio-economic and environment aspects. Flood management should have involvement of various stakeholders including concerned authorities such as urban planners, civil and water resources engineers, civil disaster defence authorities, health and social services, etc. The best flood mitigation measures from all main points of view – social, economic and environmental are natural water retention measures. Natural water retention measures cover a diversity of measures that are implemented by different sectors or considered in different planning processes dealing with water, food risk management, biodiversity protection, climate change adaptation or urban planning. Some of these measures aim to directly modify the ecosystem, while others focus on changes of practice of economic operators. The paper presents natural water retention measures suitable for application in urban areas.

Realising the potential of natural water retention measures in catchment flood management: trade‐offs and matching interests

Natural water retention measures (NWRM) are a multifunctional form of green infrastructure that can play an important role in catchment‐scale flood risk management. While green infrastructure based on natural processes is increasingly recognised as being complementary to traditional flood control strategies based on grey infrastructure in urban areas, there are a number of outstanding challenges with their widespread uptake. At a catchment scale, it is widely accepted that NWRM in upstream areas based on the concept of ‘keeping the rain where it falls’ can help reduce the risk of downstream flooding by enhancing or restoring natural hydrological processes including interception, evapotranspiration, infiltration, and ponding. However, both the magnitude of flood risk reduction and the institutional structures needed for widespread uptake of NWRM are inadequately understood. Implementing NWRM can involve trade‐offs, especially in agricultural areas. Measures based on drainage management and short rotation forestry may help ‘keep the rain where it falls’ but can result in foregone farm income. To identify situations where the implementation of NWRM may be warranted, an improved understanding of the likely reductions in downstream urban flood risk, the required institutional structures for risk management and transfer, and mutually acceptable farm compensation schemes are all needed.

Current status and restoration options for floodplains along the Danube River

Floodplains are key ecosystems of riverine landscapes and provide a multitude of ecosystem services. In most of the large river systems worldwide, a tremendous reduction of floodplain area has occurred in the last 100years and this loss continues due to pressures such as land use change, river regulation, and dam construction. In the Danube River Basin, the extent of floodplains has been reduced by 68% compared to their pre-regulation area, with the highest losses occurring in the Upper Danube and the lowest in the Danube Delta. In this paper, we illustrate the restoration potential of floodplains along the Danube and its major tributaries. Via two case studies in the Upper and Lower Danube, we demonstrate the effects of restoration measures on the river ecosystem, addressing different drivers, pressures, and opportunities in these regions. The potential area for floodplain restoration based on land use and hydromorphological characteristics amounts to 8102 km2 for the whole Danube River, of which estimated 75% have a high restoration potential. A comparison of floodplain status and options for restoration in the Upper and Lower Danube shows clear differences in drivers and pressures, but certain common options apply in both sections if the local context of stakeholders and societal needs are considered. New approaches to flood protection using natural water retention measures offer increased opportunities for floodplain restoration, but conflicting societal needs and legal frameworks may restrict implementation. Emerging issues such as climate change and invasive non-native species will need careful consideration in future restoration planning to minimize unintended effects and to increase the resilience of floodplains to these and other pressures.

Usługi ekosystemów w aspekcie zrównoważonego rozwoju obszarów miejskich

Związki między funkcjonowaniem ekosystemów a korzyściami czerpanymi przez społeczeństwo rozpatrywano już od lat 70. XX w. Prowadzone badania i analizy w tym zakresie, a także opracowanie i udoskonalenie metod szacowania wartości ekonomicznej usług ekosystemów, są powodem zmian postaw wśród decydentów i polityków. W ostatnich latach można zauważyć wzrost świadomości ekologicznej szczególnie w krajach wysokorozwiniętych, który sprawił, iż coraz częściej, zarówno w pracach naukowych jak i dokumentach dotyczących rozwoju obszarów zurbanizowanych dużo uwagi poświęca się usługom ekosystemów. Zauważono, że kondycja miast zależy od zdrowego środowiska przyrodniczego, które wytwarza szereg korzyści, a zdrowe ekosystemy stanowią podstawę zrównoważonego rozwoju miast, ponieważ pozytywnie oddziałują na dobrobyt człowieka i działalność gospodarczą. Celem artykułu jest przedstawienie aktualnego stanu wiedzy na temat teoretycznych aspektów związanych z pojęciem usługi ekosystemów oraz ich znaczenia dla zrównoważonego rozwoju obszarów miejskich. Szczególną uwagę zwrócono na działania podejmowane przez gminy w tym zakresie m.in. problem planowania przestrzennego miast w tym zachowanie: odpowiedniej ilości i jakości terenów zielonych oraz funkcjonowania ekosystemów wodnych i naturalnej retencji wody.

Sustainable floodplain management for flood prevention and water quality improvement

Although it is not possible to completely eliminate flooding in an era of climate change and intensification of extreme weather events, effective flood prevention and management in river floodplains may make a significant contribution. The land use characteristics of a catchment and river valley determine, to a great extent, the functioning of a river floodplain, as well as the quantity and size of the flood pulses in the river. The paper is focused on the role played by ecohydrology in flood risk management and water quality. From the ecohydrological perspective, river floodplains are extremely important and capacious ecosystems which, being periodically flooded, absorb flood and pollutant peaks and may minimise the danger of flooding. Increased natural water retention capacity in floodplain areas and the whole basin in the face of progressive climate change is possible through three routes: the modelling of the hydrological budget of the catchment towards the sustainable ecohydrological management of floodplains, the optimal use of existing hydrotechnical infrastructure and the implementation of ecohydrological biotechnologies. Furthermore, with such a holistic perspective, the role of river floodplains is one that also enhances the resilience of the river basin against climate and anthropogenic change, as well as increasing flood safety, improving water quality and increasing its ecosystem services for society.

A land-use-based modelling chain to assess the impacts of Natural Water Retention Measures on Europe’s Green Infrastructure

This article details the process of integrating models to answer a specific policy-driven question: ‘What could be the impact of proposed Natural Water Retention Measures (NWRMs) on Europe’s Green Infrastructure (GI)?’ It describes the new Land Use Modelling Platform (LUMP), now enabling a high spatial scale (100-m) and large coverage (pan-European), whereby several sector-specific models contribute to assessing the impact of regional-level policy on a given spatial topic of concern. The configuration (land claims and land allocations modules) and calibration (accessibility and biophysical suitability) of the LUMP are explained. Four NWRM scenarios (riparian areas, afforestation, grassland and baseline scenario) are configured to run the simulations. For the reference: year 2006, the spatial representation of GI is based on land-use features of a refined version of the CORINE Land Cover (CLC), and resumed as connected components made of nodes and links.Mathematical morphological image processing and network graph theory model, available from the free software package GUIDOS (the Joint Research Center of the European Commission), enabled the measurement of the GI connectivity and identified most critical links. Results show that the competition for land claimed by different economic sectors, combined with policy-driven rule-sets for the implementation of different NWRMs, yields very different results for the 2030 land-use projections, and subsequently for the morphology of GI. Three indicators associated with the morphology of GI are computed in order to assess the model outputs for 2030. The indicators are computed to answer the following questions: (1) How is the quantity of GI affected by each of the NWRM, and what proportion of that GI is most valuable? (2) What is the location of the most critical nodes and connectors of GI, and what land-use conversions occur under these? (3) Are the average components getting larger or smaller?Whereas the grassland measure results in the largest net increase of GI, the afforestation measure results in the overall largest number of hectares of key nodes and links within the network. Land conversions occur under the critical GI nodes and links, with a large increase in agricultural areas, especially for the riparian measure under critical nodes and the grassland measure under critical links. Also predominant is the swapping of land from pasture to forest under critical links with the afforestation measure. The riparian measure most increases the average size of GI components, and all three measures contribute to bridging two large components which were divided in the 2006 land-use map, thus increasing the size of the largest component by more than 50%.

“The organized encroachment of land developers”—Effects on urban flood management in Greater Dhaka, Bangladesh

Abstract This paper presents the results of a Global Position System (GPS) survey and questionnaire survey of 195 plot buyers in land and housing development projects located in Dhaka Metropolitan Development Plan (DMDP) area and violations of the DMDP policy on flood flow zones and retention ponds. The findings showed that developers have significantly converted 10,128.33 ha of lands in flood zones into housing projects and related project developments on natural water retention ponds violating the DMDP policy. Results highlighted that such development projects contribute to the cumulatively increasing intensity of urban floods and subsequent damages in Greater Dhaka. Review shows that although Dhaka has its flood management policies, but these are mostly involved with structural measures such as construction of embankments, floodwalls, retention ponds, and pumping stations. In addition, the paper analyzed the inherent lack of integrated planning, the lacunae within agencies in charge of urban management and resultant externalities in the built-environment. Finally, in order to protect the flood zones and retention ponds from further encroachments and severe future flood vulnerability of Greater Dhaka, the study proposed some structural and non-structural measures for policy makers to consider.

Modelling of natural water retention in the catchment basin of the Opava river during flood

The aim of the analysis involved in the article is to define the significance of separate factors affecting the natural process of retention in the catchment basin thus can assess the priorities in undertaking flood protection. The analysis was based on results achieved by using a new method how to determine water retention in the catchment basin. Resulting dependent variables of effective long-time retention, effective short-time retention, effective total retention and maximum specific runoff for single catchment basins of the Opava river, were evaluated statistically by means of linear regression and correlation analysis, stepwise regression and multiple regression. It is possible to say, that the results achieved may suggest to re-evaluate some established views concerning the role of separate factors influencing natural retention of the landscape. The results of the research testify the fact that in case of densely settled floodplain regions the combined flood protection measures, i.e. as technical and nature friendly ones should be applied. Due to relatively small collection of observations it is not possible to generalize all the conclusions absolutely, nevertheless they have a certain validity at least for the given area.

Potentials and limitations of natural flood retention by forested land in headwater catchments: evidence from experimental and model studies

AbstractAssessment of catchments water retention potential in the landscape is a common part of management plans as components of integrated flood risk management strategies. For forest land use, it has been stated that the promotion of sustainable forest management and the increase of forest land via afforestation will considerably improve flood retention. Notably, the latter should be efficient to re‐establish the natural water retention potential in anthropogenically disturbed river basins and to decrease the human‐made contribution to flood generation. However, due to obvious physical limitations (such as soil depth, porosity, and conductivity) and the frequent lack of available land for forest expansion, the role of afforestation in flood mitigation has been a topic of strong debate. This study assesses the ‘forest effect’ based on model calculations and suggests visualisations to communicate the results. For a catchment (6.8 ha) and two well‐founded land‐use scenarios, it could be shown that the peak reduction for flood events varies from 3% to 70% and is highly related to the event characteristics (especially pre‐event soil moisture). The cross compliance to other protection aims (i.e. water quality and soil protection) is part of the considerations.

Estimation and economic valuation of the forest retention capacities

Estimation and economic valuation of the forest retention capacities Based on results concerning the forest impact on water cycling an attempt was undertaken to evaluate water retention in forests. The economic value of water retention was established assuming the cost of water storage in small reservoirs built in forest areas. Calculations did not account for differences resulting from different functions of naturally retained water and that stored with the use of technical methods. Considering volume and time of water retention in forests, the annual value of natural water retention in forests calculated per average hectare of the country area was estimated at 800 zł.

Two‐phase flow infiltration equations accounting for air entrapment effects

Water infiltration into the unsaturated zone is potentially affected by air compression ahead of the wetting front. Analytical infiltration equations accounting for air compression, air counterflow, and flow hysteresis in a porous medium were derived on the basis of the Green and Ampt [1911] assumptions. Air compression ahead of the wetting front was predicted using the perfect gas law. The capillary pressure at the wetting front was found to vary between the dynamic water‐bubbling value and the dynamic air‐bubbling value of the material. These equations, accounting also for the effects of macropores near the soil surface, turned out to be simpler than the traditional Kostiakov [1932] and the Philip [1957a, b, c, d] equations. The equation parameters are physically meaningful and can be readily obtained from field measurements of the natural saturated hydraulic conductivity and soil water retention or pressure infiltrometer data. Experimental testing showed that the equations are reasonably accurate.

Natural Water Content as a Useful Index for Predicting Physical Properties of Ando :Soils in Japan

The particle-size distribution of a soil is most widely used as an index for predicting the physical properties of soils. However, for the Ando soils, since the particle-size distribution is unsuitable owing to the difficulty of dispersion, the natural water content, water retention, and plasticity have been used as an index of the physical properties of soils (1–3). In the present short communication, we report that the natural water content is a useful index for predicting physical properties such as IS-bar water content, liquid limit, bulk density in the field state and sediment volume of Ando soils in Japan, based on the analysis of a correlation table. In this experiment, the natural water content corresponded to the water content of a field-moist state and was measured by using undisturbed core samples. A high correlation between the natural water content and sediment volume for the same soil samples as those used in this study was already reported (4), and will again be described here. Table 1 list...