Linking Flow Regime, Floodplain Lake Connectivity and Fish Catch in a Large River-Floodplain System, the Volga-Akhtuba Floodplain (Russian Federation)

River-floodplain systems are amongst the most productive—but often severely impacted—aquatic systems worldwide. We explored the ecological response of fish to flow regime in a large river-floodplain system by studying the relationships between (1) discharge and inundated floodplain area, with a focus on spatial and temporal patterns in floodplain lake connectivity, and (2) flood volume and fisheries catch. Our results demonstrate a non-linear relationship between discharge and floodplain inundation with considerable hysteresis due to differences in inundation and drainage rate. Inundation extent was mostly determined by flood volume, not peak discharge. We found that the more isolated lakes (that is, lakes with a shorter connection duration to the river) are located at higher local elevation and at larger hydrological distance from the main rivers: geographical distance to the river appears a poor predictor of lake isolation. Although year-to-year fish catches in the floodplain were significantly larger with larger flood volumes in the floodplain, they were not in the main river, suggesting that mechanisms that increase catch, such as increased floodplain access or increased somatic growth, are stimulated by flooding in the floodplain, but not in the river. Fish species that profit from flooding belong to different feeding guilds, suggesting that all trophic levels may benefit from flooding. We found indications that the ecological functioning of floodplains is not limited to its temporary availability as habitat. Refugia can be present within the floodplain itself, which should be considered in the management of large rivers and their floodplain

THE INFLUENCE OF THE THREAT OF FLOODING ON HOUSING VALUES IN FARGO, NORTH DAKOTA AND MOORHEAD, MINNESOTA

The hedonic valuation method (HVM) was used to quantify the impact of the threat of flooding on housing values in Fargo, North Dakota and Moorhead, Minnesota (Fargo-Moorhead). Prices of 3,783 Fargo-Moorhead homes sold between 1995 and 1998 were regressed against structural housing characteristics, neighborhood and environmental indicators, and three flood risk variables. Being located in the 100-year floodplain lowered the sale price of an average home by $8,990 and approximately 81 percent of the price depreciation was associated with required flood insurance premiums. After the extensive 1997 flood, homes in the 100-year floodplain were on average priced$10,241 less than similar homes located outside the floodplain and before the 1997 flood event. The aftermath of publicity of the 1997 flood was specifically responsible for average 100-year floodplain homes being reduced by an additional $1,350. In contrast, homes in the 500-year floodplain on average sold for$3,100 more than similar homes not in the floodplain. It was concluded that homebuyers in Fargo-Moorhead place a value on flooding risk, that more disclosure is needed regarding the location of the 500-year floodplain, and that substantial housing value related benefits are likely to be generated by various flood mitigation projects in the area that result in a re-designation and reduction of the 100-year floodplain.Hedonic valuation method, flooding, floodplain, Fargo, Moorhead, Red River of the North, housing values, Community/Rural/Urban Development,

AHS2005: The 2005 airborne imaging spectroscopy campaign in the Millingerwaard, the Netherlands

The Millingerwaard was one of the first nature rehabilitation projects for river floodplains in the Netherlands. It therefore serves as an example project for other floodplain rehabilitation projects. As a consequence a lot of effort has been put in monitoring the vegetation succession in the floodplain. To stimulate the development of a heterogeneous landscape, a low grazing density of 1 animal (e.g., Galloway, Koniks) per 2-4 ha has been chosen. This density allows grazing whole year round and also development of forest is possible. The surface area of water changes over the year. During high floods, the whole floodplain except for the higher parts of the river dunes is flooded. This report describes the field and airborne data acquired during the AHS2005 imaging spectroscopy campaign in the Millingerwaard floodplain during the summer of 2005. The campaign is part of a research line that explores the use of hyperspectral sensors to retrieve biochemical and biophysical variables as input for ecological models using an integrated approac

Oxidation and reduction rates for organic carbon in the Amazon mainstream tributary and floodplain, inferred from distributions of dissolved gases

Concentrations of CO2, O2, CH4, and N2O in the Amazon River system reflect an oxidation-reduction sequence in combination with physical mixing between the floodplain and the mainstem. Concentrations of CO2 ranged from 150 microM in the Amazon mainstem to 200 to 300 microM in aerobic waters of the floodplain, and up to 1000 microM in oxygen-depleted environments. Apparent oxygen utilization (AOU) ranged from 80 to 250 microM. Methane was highly supersaturated, with concentrations ranging from 0.06 microM in the mainstem to 100 microM on the floodplain. Concentrations of N2O were slightly supersaturated in the mainstem, but were undersaturated on the floodplain. Fluxes calculated from these concentrations indicated decomposition of 1600 g C sq m y(-1) of organic carbon in Amazon floodplain waters. Analysis of relationships between CH4, O2, and CO2 concentrations indicated that approximately 50 percent of carbon mineralization on the floodplain is anaerobic, with 20 percent lost to the atmoshphere as CH4. The predominance of anaerobic metabolism leads to consumption of N2O on the flood plane. Elevated concentrations of CH4 in the mainstem probably reflect imput from the floodplain, while high levels of CO2 in the mainstem are derived from a combination of varzea drainage and in situ respiration

BIO-ECONOMIC DEVELOPMENT OF FLOODPLAINS: FARMING VERSUS FISHING IN BANGLADESH

This paper explores the linkages of environment and economic development in the floodplain of large rivers. There is considerable evidence that even the most vital floodplains in the world are not being managed efficiently and both economic and ecological factors need to be considered for effective management. Floodplain management policies in Bangladesh emphasize structural changes to enhance agricultural production. However, these structural changes reduce fisheries production, where the fishery is an important natural resource sector and a source of subsistence for the rural poor. We develop a model where net returns to agriculture and fisheries are jointly maximized taking into account the effect of flooding depth and timing on production. Results for a region in Bangladesh show that optimal production in a natural floodplain yields higher net returns compared to a floodplain modified by flood control structures. This finding has important implications for management policies -- neglecting the bio-economic relationship between fisheries and land use may significantly affect the long-run economic role of a river floodplain, particularly in a poor country.Community/Rural/Urban Development,

HEC-RAS hydraulic model for floodplain area in Sembrong river

The study of floodplain is significant to human life and social economy. It can be seen that by using most computer models, locations of structures affected by floodwaters, such as bridges and roads cannot be effectively compared to the floodplain location in stream floodplain analysis. The purpose of this study is to develop an output of Hydrologic Engineering Center’s River Analysis System (HEC-RAS) hydraulic model and to enable one dimensional steady flow analysis. This study is applied to Sembrong river catchment area, located in Batu Pahat. Floodplain data features such as length of streams, bank position, streamline and cross-sections were used to produce river flow and its cross-sectional shape for each station along the study area. Total of 7 flow rate values were used to indicate an increase in the water level in order to accommodate the additional amount of water that flow into river. The results show that water will overflow into the floodplain at maximum flow rate of 24 m3 /s. The hydraulic model had indicated that 33 out of 65 stations were unable to accommodate the maximum flow rate and thus will led to flooding. By developing the hydraulic model, it clearly shows that the results are more reliable and the affected area can be easily identified. The developed flood model can be a very useful tool in flood management of Sembrong river in terms of river development planning, flood mitigation measures, flood evacuation planning and addressing public awareness. This study proved that HEC-RAS is one of effective instrument for analysis and modeling

Common interests, private gains: a study of co-operative floodplain aquaculture

In recent years a number of floodplain aquaculture projects have sprung up in the Daudkandi area of Comilla District. Key to this development are a number of unique organisational and financing arrangements which facilitate the development of necessary infrastructure through issuing shares to farmers who have land in the targeted floodplain area. In February 2007, a short review was carried out to better understand how floodplain aquaculture was affecting a range of local social, economic and environmental issues.Fishery management, Flood plains, Aquaculture

Floodplain management in temperate regions : is multifunctionality enhancing biodiversity?

Background: Floodplains are among the most diverse, dynamic, productive and populated but also the most threatened ecosystems on Earth. Threats are mainly related to human activities that alter the landscape and disrupt fluvial processes to obtain benefits related to multiple ecosystem services (ESS). Floodplain management therefore requires close coordination among interest groups with competing claims and poses multi-dimensional challenges to policy-makers and project managers. The European Commission proposed in its recent Biodiversity Strategy to maintain and enhance European ecosystems and their services by establishing green infrastructure (GI). GI is assumed to provide multiple ecosystem functions and services including the conservation of biodiversity in the same spatial area. However, evidence for biodiversity benefits of multifunctional floodplain management is scattered and has not been synthesised. Methods/design: This protocol specifies the methods for conducting a systematic review to answer the following policy-relevant questions: a) what is the impact of floodplain management measures on biodiversity; b) how does the impact vary according to the level of multifunctionality of the measures; c) is there a difference in the biodiversity impact of floodplain management across taxa; d) what is the effect of the time since implementation on the impact of the most important measures; and e) are there any other factors that significantly modify the biodiversity impact of floodplain management measures? Within this systematic review we will assess multifunctionality in terms of ESS that are affected by an implemented intervention. Biodiversity indicators included in this systematic review will be related to the diversity, richness and abundance of species, other taxa or functional groups. We will consider if organisms are typical for and native to natural floodplain ecosystems. Specific inclusion criteria have been developed and the wide range of quality of primary literature will be evaluated with a tailor-made system for assessing susceptibility to bias and the reliability of the studies. The review is intended to bridge the science-policy interface and will provide a useful synthesis of knowledge for decision-makers at all governance levels

Patterns in fish assemblages in the Loire floodplain: the role of hydrological connectivity and implications for conservation

Hydrological connectivity is known to determine biodiversity patterns across large river floodplains, but it is often greatly altered by human activities. Indicators and predictors of the response of river alteration or restoration are therefore needed. Recent papers suggested that fish environmental guilds – based on species flow preferences – could be used as a tool to assess ecological status of rivers. In the Loire floodplain, we described fish assemblages across the floodplain at the onset of the dry season and we determined whether observed spatial patterns could be related to environmental variables, especially connectivity. Based on specific composition of 46 electrofished waterbodies, a hierarchical typology of the Loire floodplain assemblages was built using self-organizing maps. Each assemblage of the typology was characterized by a set of species using the indicator value method. These species sets and the composition of the assemblages revealed a gradient of flow preferences in the different assemblages identified. A stepwise discriminant analysis showed that the most important variable determining assemblage composition was the hydrological connectivity. Finally, the conclusion was made that a high connectivity level is needed to conserve native fish diversity in the Loire floodplain, notably because the number of protected and native species increased with connectivity, and because the number of exotic species increased with isolation

Potential for sustainable floodplain fisheries development: a case study of Tatabu floodplain

This study presents evidence from a case study of an ecological appraisal of Tatabu flood plain aimed at formulation management approaches for the enhancement of the fishing communities social economic and cultural realities. Tabtabu flood plain is located north of Jebba and at high water the ecosystems cover about 700 hectares. Fishing constitutes the principal economic activity of natural fish food and flora (especially phytoplankton and zooplankton) which support and favour the growth of over 26 fish species that belong to 15 families. Among the commercially important species in terms of dominance on percentage weight basis are Mochokidae, Cichlidae, Claridae and Characidae with an overall average standing crop of 88.24kg/ha based on gill net experiment. The study based on the intrinsic ecological attributes and local people willingness for sustained contribution of fisheries to food supply indicates that with adequate management Tatabu flood plain ecosystems have tremendous fishery potentials that would enhance the economic well being of the communities. Several management options that are applicable to similar plain are discusse