388 resultados para Catchments
Resumo:
Executive summary. In this report we analyse implementation costs and benefits for agricultural management practices, grouped into farming systems. In order to do so, we compare plot scale gross margins for the dominant agricultural production systems (sugarcane, grazing and banana cultivation) in the NRM regions Wet Tropics, Burdekin Dry Tropics and Mackay Whitsundays. Furthermore, where available, we present investment requirements for changing to improved farming systems. It must be noted that transaction costs are not captured within this project. For sugarcane, this economic analysis shows that there are expected benefits to sugarcane growers in the different regions through transitions to C and B class farming systems. Further transition to A-class farming systems can come at a cost, depending on the capital investment required and the length of the investment period. Obviously, the costs and benefits will vary for each individual grower and will depend on their starting point and individual property scenario therefore each circumstance needs to be carefully considered before making a change in management practice. In grazing, overall, reducing stocking rates comes at a cost (reduced benefits). However, when operating at low utilisation rates in wetter country, lowering stocking rates can potentially come at a benefit. With win-win potential, extension is preferred to assist farmer in changing management practices to improve their land condition. When reducing stocking rates comes at a cost, incentives may be applicable to support change among farmers. For banana cultivation, the results indicate that the transition to C and B class management practices is a worthwhile proposition from an economic perspective. For a change from B to A class farming systems however, it is not worthwhile from a financial perspective. This is largely due to the large capital investment associated with the change in irrigation system and negative impact in whole of farm gross margin. Overall, benefits will vary for each individual grower depending on their starting point and their individual property scenario. The results presented in this report are one possible set of figures to show the changes in profitability of a grower operating in different management classes. The results in this report are not prescriptive of every landholder. Landholders will have different costs and benefits from transitioning to improved practices, even if similar operations are practiced, hence it is recommended that landholders that are willing to change management undertake their own research and analysis into the expected costs and benefits for their own soil types and property circumstances.
Resumo:
In the Mackay Whitsunday region, the dominant grazing based operations are small intensive systems that heavily utilise soil, nutrient and chemical management practices. To improve water quality entering the Great Barrier Reef, graziers are being encouraged to adopt improved management practices. However, while there is good understanding of the management changes required to reach improved practice classification levels, there is poor understanding of the likely economic implications for a grazier seeking to move from a lower level classification to the higher level classifications. This paper provides analysis of the costs and benefits associated with adoption of intensive grazing best management practices to determine the effect on the profitability and economic sustainability of grazing enterprises, and the economic viability of capital investment to achieve best management. The results indicate that financial incentives are likely to be required to encourage smaller graziers to invest in changing their management practices, while larger graziers may only require incentives to balance the risk involved with the transition to better management practices.
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Lakes are an important component of ecosystem carbon cycle through both organic carbon sequestration and carbon dioxide and methane emissions, although they cover only a small fraction of the Earth's surface area. Lake sediments are considered to be one of rather perma-nent sinks of carbon in boreal regions and furthermore, freshwater ecosystems process large amounts of carbon originating from terrestrial sources. These carbon fluxes are highly uncer-tain especially in the changing climate. -- The present study provides a large-scale view on carbon sources and fluxes in boreal lakes situated in different landscapes. We present carbon concentrations in water, pools in lake se-diments, and carbon gas (CO2 and CH4) fluxes from lakes. The study is based on spatially extensive and randomly selected Nordic Lake Survey (NLS) database with 874 lakes. The large database allows the identification of the various factors (lake size, climate, and catchment land use) determining lake water carbon concentrations, pools and gas fluxes in different types of lakes along a latitudinal gradient from 60oN to 69oN. Lakes in different landscapes vary in their carbon quantity and quality. Carbon (C) content (total organic and inorganic carbon) in lakes is highest in agriculture and peatland dominated areas. In peatland rich areas organic carbon dominated in lakes but in agricultural areas both organic and inorganic C concentrations were high. Total inorganic carbon in the lake water was strongly dependent on the bedrock and soil quality in the catchment, especially in areas where human influence in the catchment is low. In inhabited areas both agriculture and habitation in the catchment increase lake TIC concentrations, since in the disturbed soils both weathering and leaching are presumably more efficient than in pristine areas. TOC concentrations in lakes were related to either catchment sources, mainly peatlands, or to retention in the upper watercourses. Retention as a regulator of the TOC concentrations dominated in southern Finland, whereas the peatland sources were important in northern Finland. The homogeneous land use in the north and the restricted catchment sources of TOC contribute to the close relationship between peatlands and the TOC concentrations in the northern lakes. In southern Finland the more favorable climate for degradation and the multiple sources of TOC in the mixed land use highlight the importance of retention. Carbon processing was intensive in the small lakes. Both CO2 emission and the Holocene C pool in sediments per square meter of the lake area were highest in the smallest lakes. How-ever, because the total area of the small lakes on the areal level is limited, the large lakes are important units in C processing in the landscape. Both CO2 and CH4 concentrations and emissions were high in eutrophic lakes. High availability of nutrients and the fresh organic matter enhance degradation in these lakes. Eutrophic lakes are often small and shallow, enabling high contact between the water column and the sediment. At the landscape level, the lakes in agricultural areas are often eutrophic due to fertile soils and fertilization of the catchments, and therefore they also showed the highest CO2 and CH4 concentrations. Export from the catchments and in-lake degradation were suggested to be equally important sources of CO2 and CH4 in fall when the lake water column was intensively mixed and the transport of sub-stances from the catchment was high due to the rainy season. In the stagnant periods, especially in the winter, in-lake degradation as a gas source was highlighted due to minimal mixing and limited transport of C from the catchment. The strong relationship between the annual CO2 level of lakes and the annual precipitation suggests that climate change can have a major impact on C cycling in the catchments. Increase in precipitation enhances DOC export from the catchments and leads to increasing greenhouse gas emissions from lakes. The total annual CO2 emission from Finnish lakes was estimated to be 1400 Gg C a-1. The total lake sediment C pool in Finland was estimated to be 0.62 Pg, giving an annual sink in Finnish lakes of 65 Gg C a-1.
Resumo:
The terrestrial export of dissolved organic matter (DOM) is associated with climate, vegetation and land use, and thus is under the influence of climatic variability and human interference with terrestrial ecosystems, their soils and hydrological cycles. The present study provides an assessment of spatial variation of DOM concentrations and export, and interactions between DOM, catchment characteristics, land use and climatic factors in boreal catchments. The influence of catchment characteristics, land use and climatic drivers on the concentrations and export of total organic carbon (TOC), total organic nitrogen (TON) and dissolved organic phosphorus (DOP) was estimated using stream water quality, forest inventory and climatic data from 42 Finnish pristine forested headwater catchments, and water quality monitoring, GIS land use, forest inventory and climatic data from the 36 main Finnish rivers (and their sub-catchments) flowing to the Baltic Sea. Moreover, the export of DOM in relation to land use along a European climatic gradient was studied using river water quality and land use data from four European areas. Additionally, the role of organic and minerogenic acidity in controlling pH levels in Finnish rivers and pristine streams was studied by measuring organic anion, sulphate (SO4) and base cation (Ca, Mg, K and Na) concentrations. In all study catchments, TOC was a major fraction of DOM, with much lower proportions of TON and DOP. Moreover, most of TOC and TON was in a dissolved form. The correlation between TOC and TON concentrations was strong and TOC concentrations explained 78% of the variation in TON concentrations in pristine headwater streams. In a subgroup of 20 headwater catchments with similar climatic conditions and low N deposition in eastern Finland, the proportion of peatlands in the catchment and the proportion of Norway spruce (Picea abies Karsten) of the tree stand had the strongest correlation with the TOC and TON concentrations and export. In Finnish river basins, TOC export increased with the increasing proportion of peatland in the catchment, whereas TON export increased with increasing extent of agricultural land. The highest DOP concentrations and export were recorded in river basins with a high extent of agricultural land and urban areas, reflecting the influence of human impact on DOP loads. However, the most important predictor for TOC, TON and DOP export in Finnish rivers was the proportion of upstream lakes in the catchment. The higher the upstream lake percentage, the lower the export indicating organic matter retention in lakes. Molar TOC:TON ratio decreased from headwater catchments covered by forests and peatlands to the large river basins with mixed land use, emphasising the effect of the land use gradient on the stoichiometry of rivers. This study also demonstrated that the land use of the catchments is related to both organic and minerogenic acidity in rivers and pristine headwater streams. Organic anion dominated in rivers and streams situated in northern Finland, reflecting the higher extent of peatlands in these areas, whereas SO4 dominated in southern Finland and on western coastal areas, where the extent of fertile areas, agricultural land, urban areas, acid sulphate soils, and sulphate deposition is highest. High TOC concentrations decreased pH values in the stream and river water, whereas no correlation between SO4 concentrations and pH was observed. This underlines the importance of organic acids in controlling pH levels in Finnish pristine headwater streams and main rivers. High SO4 concentrations were associated with high base cation concentrations and fertile areas, which buffered the effects of SO4 on pH.
Resumo:
The use of buffer areas in forested catchments has been actively researched during the last 15 years; but until now, the research has mainly concentrated on the reduction of sediment and phosphorus loads, instead of nitrogen (N). The aim of this thesis was to examine the use of wetland buffer areas to reduce the nitrogen transport in forested catchments and to investigate the environmental impacts involved in their use. Besides the retention capacity, particular attention was paid to the main factors contributing to the N retention, the potential for increased N2O emissions after large N loading, the effects of peatland restoration for use as buffer areas on CH4 emissions, as well as the vegetation composition dynamics induced by the use of peatlands as buffer areas. To study the capacity of buffer areas to reduce N transport in forested catchments, we first used large artificial loadings of N, and then studied the capacity of buffer areas to reduce ammonium (NH4-N) export originating from ditch network maintenance areas in forested catchments. The potential for increased N2O emissions were studied using the closed chamber technique and a large artificial N loading at five buffer areas. Sampling for CH4 emissions and methane-cycling microbial populations were done on three restored buffer areas and on three buffers constructed on natural peatlands. Vegetation composition dynamics was studied at three buffer areas between 1996 and 2009. Wetland buffer areas were efficient in retaining inorganic N from inflow. The key factors contributing to the retention were the size and the length of the buffer, the hydrological loading and the rate of nutrient loading. Our results show that although the N2O emissions may increase temporarily to very high levels after a large N loading into the buffer area, the buffer areas in forested catchments should be viewed as insignificant sources of N2O. CH4 fluxes were substantially higher from buffers constructed on natural peatlands than from the restored buffer areas, probably because of the slow recovery of methanogens after restoration. The use of peatlands as buffer areas was followed by clear changes in plant species composition and the largest changes occurred in the upstream parts of the buffer areas and the wet lawn-level surfaces, where the contact between the vegetation and the through-flow waters was closer than for the downstream parts and dry hummock sites. The changes in the plant species composition may be an undesired phenomenon especially in the case of the mires representing endangered mire site types, and therefore the construction of new buffer areas should be primarily directed into drained peatland areas.
Resumo:
Two multicriterion decision-making methods, namely `compromise programming' and the `technique for order preference by similarity to an ideal solution' are employed to prioritise 22 micro-catchments (A1 to A22) of Kherthal catchment, Rajasthan, India and comparative analysis is performed using the compound parameter approach. Seven criteria - drainage density, bifurcation ratio, stream frequency, form factor, elongation ratio, circulatory ratio and texture ratio - are chosen for the evaluation. The entropy method is employed to estimate weights or relative importance of the criterion which ultimately affects the ranking pattern or prioritisation of micro-catchments. Spearman rank correlation coefficients are estimated to measure the extent to which the ranks obtained are correlated. Based on the average ranking approach supported by sensitivity analysis, micro-catchments A6, A10, A3 are preferred (owing to their low ranking) for further improvements with suitable conservation and management practices, and other micro-catchments can be processed accordingly at a later phase on a priority basis. It is concluded that the present approach can be explored for other similar situations with appropriate modifications.
Resumo:
Probable maximum precipitation (PMP) is a theoretical concept that is widely used by hydrologists to arrive at estimates for probable maximum flood (PMF) that find use in planning, design and risk assessment of high-hazard hydrological structures such as flood control dams upstream of populated areas. The PMP represents the greatest depth of precipitation for a given duration that is meteorologically possible for a watershed or an area at a particular time of year, with no allowance made for long-term climatic trends. Various methods are in use for estimation of PMP over a target location corresponding to different durations. Moisture maximization method and Hershfield method are two widely used methods. The former method maximizes the observed storms assuming that the atmospheric moisture would rise up to a very high value estimated based on the maximum daily dew point temperature. On the other hand, the latter method is a statistical method based on a general frequency equation given by Chow. The present study provides one-day PMP estimates and PMP maps for Mahanadi river basin based on the aforementioned methods. There is a need for such estimates and maps, as the river basin is prone to frequent floods. Utility of the constructed PMP maps in computing PMP for various catchments in the river basin is demonstrated. The PMP estimates can eventually be used to arrive at PMF estimates for those catchments. (C) 2015 The Authors. Published by Elsevier B.V.
Resumo:
Redd counting is an integral part of most Fishery Officers duties. The number and distribution of salmonid redds throughout salmonid catchments provides invaluable information on the range and extent of spawning by both salmon and sea trout. A project was initiated by the Fisheries Science and Management Team of Central Area, North West Region in England in liaison with the Flood Defence function. The main objective of this project was to assess redd count data for Central Area and attempt to quantify these data in order to produce a grading system that would highlight key salmonid spawning areas. By showing which were the main areas for salmon and sea trout spawning, better informed decisions could be made on whether or not in-stream Flood Defence works should be given the go-ahead. The main salmonid catchments in Central Area were broken into individual reaches, approximately 1 km in length. The number of redds in these individual reaches were then calculated and a density per lkm value was obtained for each reach. A grading system was devised which involved looking at the range of density per km values and dividing this by five to produce 5 classes, A - E. A sixth class (F) was used where the density per Ion value was 0.00. This grading system was calculated at two levels of detail. Grades for salmon and sea trout were produced for each individual catchment and also on an Area-wide level. Maps were produced using a range of colours to represent the grade for each reach. These maps provide a highly useful overview of the status of salmonid spawning for each catchment over individual years and highlight the key salmon and sea trout spawning areas in each catchment. These maps and the associated summary data should now provide Flood Defence and Fisheries staff with a fairly detailed overview of the status of spawning in any location within the. main salmonid catchments in Central Area. Although these maps are very useful they should only be used as a guide. The current practice of consulting with the local Fishery Officer should be continued to ensure that expert local knowledge is taken into account.
Resumo:
This is the Visual survey ERS Dane, Weaver & Bollin Catchments produced by the Environment Agency in 2005. Visual surveys of the River Dane downstream of the confluence with the Swettenham Brook, the River Weaver, and the River Bollin catchment in the EA Northwest South area of England were undertaken between 3rd and 9th February 2005 with the aim of identifying the spatial distribution and relative quality of exposed Riverine sediments (ERS). The potential value of these ERS in terms of likely habitat quality for ERS invertebrate communities was determined by recording a suite of appropriate environmental variables. Following an initial cartographical analysis of reaches likely to contain ERS, tens of kilometres of riverbank were inspected and 67 areas of ERS were selected for detailed visual survey. Site characteristics ranged widely both between and within catchments, with habitat quality ranging from poor to very high.
Resumo:
This is the report on the Crayfish Survey of the Weaver, Dane, Goyt and Etherow catchments from 1998 by the Environment Agency. The aims of this report are: Firstly, to present the findings of the crayfish survey and details of the sites visited. Secondly to present the information on distribution maps with past records so that the current status can be seen and finally to use this information so that recommendations for the conservation of native crayfish can be made in accordance with the national action plan for this species and the Environment Agency’s Species Management Programme. The report contains sections on background, going through legislation, distribution and requirements of both native and non-native crayfish. Sections on methodology, results and discussion, conclusion and recommendations. The appendix I contains maps showing the sampling points locations. Details of sampling sites are summarized in appendix II. Appendix III contains previous crayfish records and Appendix IV shows the field data recording form. Finally, a collection of photographs are displayed in appendix V.
Resumo:
This is the report on the strategic fisheries stock assessment survey of the minor catchments in South West Cumbria 1996 with particular reference to salmonids, produced by North West Water in 1994. The 1996 Minor Catchment survey indicates variations in salmonid production within these catchments. Survey results indicate that production may be reaching its limit in certain areas whilst others are underachieving and others are unsuitable for salmonid production. Trout production within the catchments is higher and more widespread than that of salmon. Water quality levels vary considerably between catchments and intra-annually within individual catchments. The need for selective habitat surveys, with a view to habitat improvement schemes (H.I.S) is discussed. This report formed a basis for subsequent reports, thus, allowing data comparisons and analysis of production level fluctuations. It was the most extensive assessment of these catchments to date, taking into account comparisons with the new National Database on salmonid production in England and Wales.
Resumo:
The Channel Catchments Cluster (3C) aims to capitalise on outputs from some of the recent projects funded through the INTERREG IVa France (Channel) England programme. The river catchment basins draining into the Channel region drain an area of 137,000km2 and support a human population of over 19M. Throughout history, these catchments, rivers and estuaries have been centres of habitation, developed through commerce and industry, providing transport links to hinterland areas. These catchments also provide drinking water and food through provision of agriculture, fisheries and aquaculture. In addition, many parts of the region are also economically important now for the tourism and leisure industries. Consequently, there is a need to manage the balance of these many and varied human activities within the catchments, rivers, estuaries and marine areas to ensure that they are maintained or restored to good environmental condition . This document highlights some of the recent work carried out by projects within the INTERREG IVa programme that provide tools and techniques to assist in the achievement of these goals.
Resumo:
Although the narrow stretch of water that separates England from France has seen both welcome (and occasionally less welcome) exchanges during the past thousand years, this physical challenge to the movement of people has certainly served to obstruct collaborative efforts that might establish a more sustainable economy in our part of Europe. Since 2009, the European Regional Development Fund (ERDF)-supported Interreg Programme France (Channel) England Region has actively supported efforts by organisations in France and England to work ever more closely together, to share good practice and to devise new ways to support sustainable development in the Region. The initiatives are certainly rooted in excellent research, but they have also been driven by the real needs of the Region and in all cases partners have worked to develop practical tools that can be readily applied in both France and England. The Channel Catchment Cluster (3C) builds on this growing tradition of cross-border cooperation to bring together the very best new knowledge from recent Anglo-French teamwork. The contents of this Compendium are the result of a wide variety of grass-roots initiatives that have benefitted enormously from a cross-border meeting of minds. The Cluster has brought together several of these cross-border teams to discuss their work and to share good practice in the dissemination and application of novel tools for environmental protection. This Compendium therefore not only presents a 'snapshot' of the wide variety of environmental protection and management tools that have emerged from the France (Channel) England Region, it also summarises where they stand on their 'pathway to impact'. There is clearly much more that can be achieved by future cross-border efforts in our Region, but I believe that this Compendium provides an excellent basis for future action. Professor Huw Taylor University of Brighton UK