• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5
  • 1
  • Tagged with
  • 7
  • 7
  • 7
  • 4
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Adaptation to flooding in low-income urban settlements of the least developed countries : a case of Dhaka East, Bangladesh

Haque, Anika Nasra January 2018 (has links)
Low-income urban settlements in the Least Developed Countries (LDCs) present an extreme case where catastrophic hazards (natural events) and chronic hazards (developed through lack of basic services) overlap. These low-income urban populations often occupy informal settlements that are particularly exposed to natural hazards such as flooding, and their vulnerability also reflects multiple deficiencies arising from their lack of basic services; they accordingly face the greatest challenges to adapt. The research reported in this thesis aims (i) to understand the adaptation processes of the urban poor to flooding; (ii) to develop new knowledge about bottom-up ways in which adaptation to flooding emerges and can be enhanced within households and communities in low-income urban settlements; and (iii) to identify how relevant organizations can contribute effectively to the adaptation process, from a more top-down perspective. The particular case study for the research is located in Dhaka East, where there is both high vulnerability to flooding, and also a significant proportion of the low-income population. The research has adopted a mixed methods approach involving different data collection methods primarily governed by the different scales and actors being investigated, i.e. households, communities and organizations (including government and NGOs). Hence, a questionnaire survey, focus group discussions, semi-structured interviews and transect walks have all been undertaken. The diverse forms of data deriving from these methods have been integrated using a qualitative form of systems analysis, to understand the relationships amongst the key variables in the vulnerability and adaptation system under investigation. The research has also developed a form of grounded theory on the processes whereby adaptive behaviour is learned and diffused in amongst the population at risk, and how more organizational-level procedures can positively influence these processes, and be improved where necessary. The research contributes to the advancement of knowledge about (a) the vulnerability of urban poor to flooding; (b) the adaptation process of the urban poor to flooding; (c) the role of organizations in affecting both vulnerability and adaptation amongst the urban poor; (d) a research methodology appropriate for exploring such inter-sectoral and interdisciplinary research issues. The study further provides relevant recommendations, based on conclusions from the systems analyses, which are potentially applicable in similar contexts in the LDCs in helping low-income urban populations to adapt more successfully to flooding. Notably, although the research focuses on adaptation of the urban poor to flooding in Dhaka, its conceptual, methodological and research findings are likely to be applicable in other LDCs where the urban poor are subjected to environmental risks.
2

Assessing impacts of climate change on Kansas water resources: rainfall trends and risk analysis of water control structures

Rahmani, Vahid January 1900 (has links)
Doctor of Philosophy / Department of Biological & Agricultural Engineering / Stacy L. Hutchinson / Precipitation impacts hydrologic structures, agricultural production, water resources management, and recreational activities, all of which significantly affect a state’s economy. Water control structure design is based on the maximum runoff rate resulting from storms with a specific return period and duration. The Rainfall Frequency Atlas (National Weather Service Technical Paper 40, 1961) (TP-40) provided statistical rainfall analysis as the basis for hydrologic structure design until the information was updated for Kansas in February 2013 (National Oceanic and Atmospheric Administration Atlas 14, volume 8) (Atlas-14). With growing concern about the effects of global climate change and predictions of more precipitation and extreme weather events, it is necessary to explore rainfall distribution patterns using the most current and complete data available. In this work, the changes in rainfall patterns were studied using the daily rainfall data from 23 stations in Kansas and 15 stations from adjacent states with daily rainfall data of 1890 through 2012. Analysis showed an increase in extreme precipitation events in Kansas with increase in magnitude from the northwest to southeast part of the state. A comparison of results of the TP-40 analysis to period 1980–2009, showed that approximately 84% of the state had an increase in short-term rainfall event magnitudes. In addition, trend analyzes on the total annual rainfall indicated a gradual increase at 21 out of 23 stations, including eight statistically significant trends. A change-point analysis detected a significant sudden change at twelve stations as early as 1940 and as recently as 1980. The increasing trend, particularly after the significant change-points, is useful in updating water management plans and can assist with agricultural production decisions such as crop selection and new plant variety development. A comparison between 10-yr, 24-hr storms from TP-40 and Atlas-14 indicated a change of -12% to 5% in Kansas. However, the number of exceedances from the 10-yr, 1-, 2-, 3-, 4-, 7-, and 10-day storms demonstrated a tendency towards more exceedances, particularly in the last five decades. Results of this study are useful for hydrologic structure design and water resources management in order to prevent accepting additional risk of failure because of the current changing climate.
3

Adaptation of agriculture to climate change in Quebec : the co-construction of agricultural policies in the RCM of Haut-Richelieu

Akkari, Cherine 05 1900 (has links)
Les facteurs climatiques ainsi bien que les facteurs non-climatiques doivent être pris en considération dans le processus d'adaptation de l'agriculture aux changements et à la variabilité climatiques (CVC). Ce changement de paradigme met l'agent humain au centre du processus d'adaptation, ce qui peut conduire à une maladaptation. Suite aux débats sur les changements climatiques qui ont attiré l'attention scientifique et publique dans les années 1980 et 1990, l'agriculture canadienne est devenue un des points focaux de plusieurs études pionnières sur les CVC, un phénomène principalement dû à l’effet anthropique. Pour faire face aux CVC, ce n’est pas seulement la mitigation qui est importante mais aussi l’adaptation. Quand il s'agit de l'adaptation, c'est plutôt la variabilité climatique qui nous intéresse que simplement les augmentations moyennes des températures. L'objectif général de ce mémoire de maîtrise est d'améliorer la compréhension des processus d'adaptation et de construction de la capacité d'adaptation ai niveau de la ferme et de la communauté agricole à travers un processus ascendant, c’est-à-dire en utilisant l'approche de co-construction (qui peut également être considéré comme une stratégie d'adaptation en soi), pour développer une gestion et des outils de planification appropriés aux parties prenantes pour accroître ainsi la capacité d'adaptation de la communauté agricole. Pour y arriver, l'approche grounded theory est utilisée. Les résultats consistent de cinq catégories interdépendantes de codes élargis, conceptuellement distinctes et avec un plus grand niveau d'abstraction. La MRC du Haut-Richelieu a été choisie comme étude de cas en raison de plusieurs de ses dimensions agricoles, à part de ses conditions biophysiques favorables. 15 entrevues ont été menées avec les agriculteurs. Les résultats montrent que si certains agriculteurs ont reconnu les côtés positifs et négatifs des CVC, d’autres sont très optimistes à ce sujet comme se ils ne voient que le côté positif; d'où la nécessité de voir les deux côtés des CVC. Aussi, il y a encore une certaine incertitude liée aux CVC, qui vient de la désinformation et la désensibilisation des agriculteurs principalement en ce qui concerne les causes des CVC ainsi que la nature des événements climatiques. En outre, et compte tenu du fait que l'adaptation a plusieurs caractéristiques et types, il existe de nombreux types d'adaptation qui impliquent à la fois l'acteur privé et le gouvernement. De plus, les stratégies d'adaptation doivent être élaborées conjointement par les agriculteurs en concert avec d'autres acteurs, à commencer par les agronomes, car ils servent en tant que relais important entre les agriculteurs et d'autres parties prenantes telles que les institutions publiques et les entreprises privées. / Climatic as well as non-climatic factors should be taken into consideration in the process of agricultural adaptation to climate change and variability. Agricultural adaptation places the human agent at the centre of the adaptation process, which can lead to maladaptation. Following the discussions on climate change that have attracted scientific and public attention during the 1980s and 1990s, Canadian agriculture has become a focal point of several pioneering studies on climate change and variability (CCV), a phenomenon mainly due to the anthropogenic effect. To deal with CCV, it is not only mitigation that is important but also adaptation. When it comes to adaptation, it is rather climate variability that interests us than just the average increases in temperatures. The overall objective of this MSc thesis is to improve the understanding of the processes of adaptation and adaptive capacity at the farm and the farming community through a bottom-up process, i.e. using the approach of co-construction (which can also be considered as an adaptation strategy in itself), to develop appropriate management and planning tools and to build a better ability to adapt in the farming community. To achieve this, the grounded theory approach is used. The end results are five interrelated categories of expanded codes, conceptually distinct and with a greater level of abstraction. The RCM of Haut-Richelieu was chosen as the study site because of its several agricultural aspects, aside from its favourable biophysical conditions. 15 interviews were conducted with farmers. The results show that while some farmers recognized the positive and the negative side of CCV, the others are very optimistic about it as if they only see the positive side; hence the need to see both sides of CCV. Also, there is still some uncertainty related to CCV, which comes from disinformation and desensitization of the farmers mainly in relation to the causes of CCV along with the nature of climatic events. Moreover and given the fact that adaptation has many characteristics and types, there are many types of adaptation that involve both the private actor and the government. Furthermore, adaptation strategies should be developed jointly by farmers in concert with other actors, starting with the agronomists because they serve as important relays between farmers and other stakeholders such as public institutions and private companies.
4

Sustainable utilisation of Table Mountain Group aquifers

Duah, Anthony A. January 2010 (has links)
<p>The Table Mountain Group (TMG) Formation is the lowest member of the Cape Supergroup which consists of sediments deposited from early Ordovician to early Carboniferous times, approximately between 500 and 340 million years ago. The Table Mountain Group (TMG) aquifer system is&nbsp / exposed along the west and south coasts of South Africa. It is a regional fractured rock aquifer that has become a major source of bulk water supply to&nbsp / meet the agricultural and urban water requirements of the Western and Eastern Cape Provinces of South Africa. The TMG aquifer system comprises of an approximately 4000 m thick sequence of quartz arenite and minor shale layers deposited in a shallow, but extensive, predominantly eastwest striking&nbsp / asin, changing to a northwest orientation at the west coast. The medium to coarse grain size and relative purity of some of the quartz arenites,&nbsp / together with their well indurated nature and fracturing due to folding and faulting in the fold belt, enhance both the quality of the groundwater and its&nbsp / exploitation potential for agricultural and domestic water supply purposes and its hot springs for recreation. The region is also home to some unique&nbsp / and indigenous floral species (fynbos) of worldwide importance. These and other groundwater dependent vegetation are found on the series of&nbsp / mountains, mountain slopes and valleys in the Cape Peninsula. The hydrogeology of the TMG consists of intermontane and coastal domains which&nbsp / have different properties but are interconnected. The former is characterized by direct recharge from rain and snow melt, deep groundwater circulation with hot springs and low conductivity groundwater. The coastal domain is characterized by shallow groundwater occurrence usually with moderate to&nbsp / poor quality, indirect recharge from rainfall of shallow circulation and where springs occur they are usually cold. The sustainable utilization of the TMG&nbsp / aquifer addressed the issues of the groundwater flow dynamics, recharge and discharge to and from the aquifer / challenges of climate change and climate variability and their potential impact on the aquifer system. The concept of safe yield, recharge and the capture principle and the integration of&nbsp / sustainable yield provided the basis for sustainable utilization with the adaptive management approach. Methodology used included the evaluation of&nbsp / recharge methods and estimates in the TMG aquifer and a GIS based water balance recharge estimation. The evaluation of natural discharges and&nbsp / artificial abstractions from the TMG aquifer system as well as its potential for future development. The Mann-Kendal trend analysis was used to test historical and present records of temperature and rainfall for significant trends as indication for climate variability and change. The determination of&nbsp / variability index of rainfall and standard precipitation index were additional analyses to investigate variability. The use of a case study from the Klein&nbsp / (Little) Karoo Rural Water Supply Scheme (KKRWSS) within the TMG study area was a test case to assess the sustainable utilization of TMG aquifers.&nbsp / Results show that recharge varies in time and space between 1% and 55% of MAP as a result of different hydrostratigraphic units of the TMG based on&nbsp / geology, hydrology, climate, soil, vegetation and landuse patterns however, the average recharge is from 1% to 5% of MAP. The TMG receives recharge&nbsp / mainly through its 37,000 km2 of outcrop largely exposed on mountainous terrain. Natural discharges from the TMG include 11 thermal and numerous&nbsp / cold spring discharges, baseflow to streams and reservoirs, and seepage to the ocean. Results from this study also show increasing temperature&nbsp / trend over the years while rainfall trend generally&nbsp / remain unchanged in the study area. Rainfall variability persists hence the potential for floodsand droughts in the region remain. Global and Regional Models predict about 10% to 25% reduction in rainfall and increase in variability in future. Impacts of&nbsp / his change in climate will affect the different types of aquifers in various ways. Increase in temperature and reduction in rainfall will increase&nbsp / evapotranspiration, reduce surface flows and eventually reduce shallow aquifer resources. Coastal aquifers risk upsurge in salinisation from sea level&nbsp / rise and increase in abstractions from dwindling surface water resources. While floods increase the risk of contamination to shallow aquifers droughts&nbsp / put pressure on all aquifers especially deep aquifers which are considered to be more reliable due to the fact that they are far removed from surface conditions. Future population growth and increase in freshwater demand will put more pressure on groundwater. Recharge to groundwater have been&nbsp / over-estimated in certain areas in the past leading to high abstraction rates from boreholes causing extensive groundwater storage depletion evident by high decline in groundwater levels in these areas and hampering sustainable management of the aquifer resources. Over-abstraction have resulted in&nbsp / loss of stream flow and baseflow reduction to streams during summer, complete loss of springs and reduction of flow to others. Flow to wetlands,&nbsp / riparian vegetation, and sometimes loss and shifts in dependent ecosystems have also resulted from over-abstraction. Sustainability has spatial and&nbsp / temporal implications due to changing climate and demand. The study recommends adaptive management practices in which several factors are&nbsp / considered in managing groundwater together with surface water resources in order to maintain ecological and environmental integrity. The KKRWSS&nbsp / and other groundwater supply schemes in the Western and Eastern Cape Provinces demonstrate the huge potential of the TMG to provide freshwatersupply for domestic and irrigation water needs however, the huge decline in groundwater levels due to over-abstraction in the KKRWSS and&nbsp / other groundwater schemes underscores the need for sustainable utilization of the TMG groundwater resources for present and future generations with&nbsp / minimal impacts on the quality, dependent hydrological and ecosystems as well as the environment.</p>
5

Sustainable utilisation of Table Mountain Group aquifers

Duah, Anthony A. January 2010 (has links)
<p>The Table Mountain Group (TMG) Formation is the lowest member of the Cape Supergroup which consists of sediments deposited from early Ordovician to early Carboniferous times, approximately between 500 and 340 million years ago. The Table Mountain Group (TMG) aquifer system is&nbsp / exposed along the west and south coasts of South Africa. It is a regional fractured rock aquifer that has become a major source of bulk water supply to&nbsp / meet the agricultural and urban water requirements of the Western and Eastern Cape Provinces of South Africa. The TMG aquifer system comprises of an approximately 4000 m thick sequence of quartz arenite and minor shale layers deposited in a shallow, but extensive, predominantly eastwest striking&nbsp / asin, changing to a northwest orientation at the west coast. The medium to coarse grain size and relative purity of some of the quartz arenites,&nbsp / together with their well indurated nature and fracturing due to folding and faulting in the fold belt, enhance both the quality of the groundwater and its&nbsp / exploitation potential for agricultural and domestic water supply purposes and its hot springs for recreation. The region is also home to some unique&nbsp / and indigenous floral species (fynbos) of worldwide importance. These and other groundwater dependent vegetation are found on the series of&nbsp / mountains, mountain slopes and valleys in the Cape Peninsula. The hydrogeology of the TMG consists of intermontane and coastal domains which&nbsp / have different properties but are interconnected. The former is characterized by direct recharge from rain and snow melt, deep groundwater circulation with hot springs and low conductivity groundwater. The coastal domain is characterized by shallow groundwater occurrence usually with moderate to&nbsp / poor quality, indirect recharge from rainfall of shallow circulation and where springs occur they are usually cold. The sustainable utilization of the TMG&nbsp / aquifer addressed the issues of the groundwater flow dynamics, recharge and discharge to and from the aquifer / challenges of climate change and climate variability and their potential impact on the aquifer system. The concept of safe yield, recharge and the capture principle and the integration of&nbsp / sustainable yield provided the basis for sustainable utilization with the adaptive management approach. Methodology used included the evaluation of&nbsp / recharge methods and estimates in the TMG aquifer and a GIS based water balance recharge estimation. The evaluation of natural discharges and&nbsp / artificial abstractions from the TMG aquifer system as well as its potential for future development. The Mann-Kendal trend analysis was used to test historical and present records of temperature and rainfall for significant trends as indication for climate variability and change. The determination of&nbsp / variability index of rainfall and standard precipitation index were additional analyses to investigate variability. The use of a case study from the Klein&nbsp / (Little) Karoo Rural Water Supply Scheme (KKRWSS) within the TMG study area was a test case to assess the sustainable utilization of TMG aquifers.&nbsp / Results show that recharge varies in time and space between 1% and 55% of MAP as a result of different hydrostratigraphic units of the TMG based on&nbsp / geology, hydrology, climate, soil, vegetation and landuse patterns however, the average recharge is from 1% to 5% of MAP. The TMG receives recharge&nbsp / mainly through its 37,000 km2 of outcrop largely exposed on mountainous terrain. Natural discharges from the TMG include 11 thermal and numerous&nbsp / cold spring discharges, baseflow to streams and reservoirs, and seepage to the ocean. Results from this study also show increasing temperature&nbsp / trend over the years while rainfall trend generally&nbsp / remain unchanged in the study area. Rainfall variability persists hence the potential for floodsand droughts in the region remain. Global and Regional Models predict about 10% to 25% reduction in rainfall and increase in variability in future. Impacts of&nbsp / his change in climate will affect the different types of aquifers in various ways. Increase in temperature and reduction in rainfall will increase&nbsp / evapotranspiration, reduce surface flows and eventually reduce shallow aquifer resources. Coastal aquifers risk upsurge in salinisation from sea level&nbsp / rise and increase in abstractions from dwindling surface water resources. While floods increase the risk of contamination to shallow aquifers droughts&nbsp / put pressure on all aquifers especially deep aquifers which are considered to be more reliable due to the fact that they are far removed from surface conditions. Future population growth and increase in freshwater demand will put more pressure on groundwater. Recharge to groundwater have been&nbsp / over-estimated in certain areas in the past leading to high abstraction rates from boreholes causing extensive groundwater storage depletion evident by high decline in groundwater levels in these areas and hampering sustainable management of the aquifer resources. Over-abstraction have resulted in&nbsp / loss of stream flow and baseflow reduction to streams during summer, complete loss of springs and reduction of flow to others. Flow to wetlands,&nbsp / riparian vegetation, and sometimes loss and shifts in dependent ecosystems have also resulted from over-abstraction. Sustainability has spatial and&nbsp / temporal implications due to changing climate and demand. The study recommends adaptive management practices in which several factors are&nbsp / considered in managing groundwater together with surface water resources in order to maintain ecological and environmental integrity. The KKRWSS&nbsp / and other groundwater supply schemes in the Western and Eastern Cape Provinces demonstrate the huge potential of the TMG to provide freshwatersupply for domestic and irrigation water needs however, the huge decline in groundwater levels due to over-abstraction in the KKRWSS and&nbsp / other groundwater schemes underscores the need for sustainable utilization of the TMG groundwater resources for present and future generations with&nbsp / minimal impacts on the quality, dependent hydrological and ecosystems as well as the environment.</p>
6

The vulnerability of Latvia’s agriculture: Farm level response to climatic and non-climatic stimuli

Buseva, Teiksma January 2011 (has links)
Agriculture is a climate sensitive sector whether it changes moderately and slowly or radicallyand rapidly. Many studies that focus on the vulnerability of agriculture, use climate scenariosand crop models to assess the potential impacts. This study seeks to identify (1) farmers‘awareness and perceptions of climate variability and change; (2) the types of adjustments theyhave made in their farming practices in response to these changes (farm responses, adaptivestrategies); and (3) other external factors (government policies, social, technological andeconomic conditions) that have significant impact on the farming activities.The results indicate that climate change and variability already have and will have mostlynegative impacts on agriculture. Prolonged dry spells and heat in the summer, less summerrain combined with higher temperatures, more heavy rainfall, more forest or grass fires andextreme weather: drought, flood, storms have been identified as highest climatic burdens toagriculture. An advanced start of the growing season is the the only truly positive change forthe majority of farmers. Apart from that several non-climatic factors were identified assignificant, among them political: high level of bureaucracy, lack of public trust in socialinstitutions, political instability; economical: incentives, for example tax exemption orreduction, access to subsidies and funds, economic growth and development, long-lastingeconomic recession; technological and infrastructural: access to advanced technologies,infrastructure and settlement development and poor road and railroad system; and social:population migration within Europa, ageing of population and population decrease. Thesesocio-economic factors play significant roles in overcoming the risks and building adaptivecapacity. This study shows that a variety of strategies and methods have been applied toreduce the vulnerability. Most often it is a farm level managerial decision, like, adjustedtiming of farm operations, changed crop variety and types, reduced number of livestock,improved technological base or increased income by off farm jobs.Finally we can conclude that even though individual farms have capacity to reducevulnerability, one must not underestimate the role of government and industry to decrease thedamages, take advantage of opportunities or cope with consequences. Farmer decision tomake changes in farming activities is rarely based on one risk alone.
7

The role of climate and land use change in Lake Urmia desiccation

Fazel Modares, N. (Nasim) 16 November 2018 (has links)
Abstract Wetlands in arid and semi-arid regions are complex fragile ecosystems that are critical in maintaining and controlling environmental quality and biodiversity. These wetlands and specially closed lake systems depend on support processes in upstream parts of the basin or recharge zone, as small changes in river flow regime can cause significant changes in lake level, salinity and productivity. Recent strong alterations in river flow regimes due to climate and land use change have resulted in ecosystem degradation and desiccation of many saline lakes in arid and semi-arid regions. Because of the low economic value of these lakes, their hydrology has not been monitored accurately, making it difficult to determine water balance and assess the role of water use and climate in lake desiccation. Furthermore, available data are usually of coarse resolution on both spatial and temporal scale. New frameworks using all available data and refining existing information on lake basins were developed in this thesis to assess regional differences in water resource availability, impacts of human activities on river flow regime alteration and agricultural land use change. The frameworks were applied to study causes and impacts of desiccation of a major lake, Lake Urmia, one of the largest saltwater lakes on Earth. This highly endangered ecosystem is on the brink of a major environmental disaster resembling that around the Aral Sea. The spatial pattern of precipitation across the Lake Urmia basin was investigated, to shed light on regional differences in water availability. Using large numbers of rainfall records and a wide array of statistical descriptors, precipitation across space and time was evaluated. Another important research component involved examining streamflow records for headwaters and lowland reaches of the Lake Urmia basin, in order to determine whether observed changes are mainly due to climate change or anthropogenic activities (e.g. water withdrawal for domestic and irrigation purposes). Principal component and clustering analyses of all available precipitation data for the lake basin revealed a heterogeneous precipitation pattern, but also permitted delineation of three homogeneous precipitation areas within the region. Further analysis identified variation in seasonal precipitation as the most important factor controlling the spatial precipitation pattern in the basin. The results showed that climate change impact on headwaters is insignificant and that irrigation is the main driving force for river flow regime alterations in the basin. This is supported by evidence that the headwaters have relatively remained unaffected by agriculture and by lack of significant changes in the historical records. The approach presented, involving clear in terpretation of existing information, can be useful in communicating land use and climate change information to decision makers and lake restoration planners. / Tiivistelmä Kuivilla aridisilla ja semiaridisilla alueilla sijaitsevat kosteikot ovat hauraita ekosysteemejä. Ne ovat myös tavallista tärkeämpiä, koska ne ylläpitävät ja säätelevät ympäristön laatua sekä luonnon monimuotoisuutta. Nämä kosteikot, kuten valtaosa muistakin kosteikoista, ovat riippuvaisia vesistöalueen ylemmillä osilla tehdyistä toimista kuten vesistöjen säännöstelystä. Jopa pienet muutokset jokien virtauksissa voivat aiheuttaa merkittäviä muutoksia järvien vedenpinnan korkeuteen, suolapitoisuuteen ja tuottavuuteen. Viimeaikaiset ilmastonmuutoksen ja maankäytön muutosten aiheuttamat voimakkaat muutokset jokien virtaamiin ovat johtaneet ekosysteemien rappeutumiseen sekä monien suolajärvien kuivumiseen kuivilla ja puolikuivilla alueilla. Kuivilla alueilla sijaitsevien suolajärvien hydrologiaa ei ole tarkkailtu riittävästi niiden alhaisemman taloudellisen arvon vuoksi. Se hankaloittaa vesitaseen määrittämistä. Tarkkojen tietojen puuttuessa on vaikea arvioida myös sitä, miten vedenkäyttö ja ilmasto ovat vaikuttaneet järvien kuivumiseen. Lisäksi saatavilla olevat tiedot ovat yleensä sekä ajallisesti että alueellisesti epätarkkoja. Analysointiin tarvittavien tietojen ja välineiden puute saattaa pahimmillaan johtaa ristiriitaisiin oletuksiin. Väitöstyön päätavoite on tarjota puitteet, joilla parannetaan ymmärrystä vesivarojen alueellisista eroista, ihmisen toiminnan vaikutuksista jokien virtausten muutoksiin ja maatalouden maankäytön muutoksista käyttäen kaikkea saatavilla olevaa dataa sekä täsmentäen samalla vesistöistä jo olemassa olevaa tietoa. Väitöskirja tutkii yhden suuren järven kuivumisen syitä ja seurauksia. Urmiajärvi on yksi maapallon suurimmista suolajärvistä sekä erittäin uhanalainen ekosysteemi. Järvi on samankaltaisen ympäristökatastrofin partaalla, joka aiheutti Araljärven kuivumisen. Väitöskirja antaa tietoa veden saatavuuden alueellisista eroista tutkimalla sademäärien alueellista jakautumista Urmiajärven valuma-alueella. Tutkielmassa arvioidaan sadannan ajallista ja paikallista vaihtelua erilaisten tilastollisten menetelmien avulla. Tutkielman toinen tärkeä osa keskittyy vesialtaan latvavesistön ja tasankoalueiden valumatietoihin. Tämän osuuden päätavoite on määritellä johtuvatko havaitut muutokset järvessä pääasiassa ilmastonmuutoksesta vai ihmisen toiminnasta kuten kastelusta. Sadantatietojen pääkomponentti- ja ryhmittelyanalyysien tulokset osoittavat, että Urmiajärven allas on sadannaltaan heterogeeninen alue. Analyysi johti seudun jakamiseen kolmeen homogeeniseen sadanta-alueeseen. Analyysi osoitti, että sademäärien kausittainen vaihtelu on merkittävin järvialtaan alueellisiin sademääriin vaikuttava tekijä. Tulokset osoittavat, että ilmastonmuutoksen vaikutukset latvavesistöön eivät olleet merkittäviä ja keinokastelu on ylivoimaisesti merkittävin järvialtaan jokien virtausten muutoksiin vaikuttava tekijä. Tätä johtopäätöstä tukee se tosiseikka, että maanviljelys ei ole juurikaan vaikuttanut latvavesistöihin eikä niissä näy historiallisten lähteiden perusteella merkittäviä muutoksia. Tutkimuksen hyöty on siinä, että se tulkitsee saatavilla olevan tiedon selkeästi, joka on avuksi, kun maankäyttöön ja ilmastonmuutokseen liittyviä tietoja välitetään päättäjille ja järven kunnostusta suunnitteleville tahoille.

Page generated in 0.17 seconds