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Identification of Influential Climate Indicators, Prediction of Long-term Streamflow and Great Salt Lake Elevation Using Machine Learning ApproachShrestha, Niroj K. 01 May 2012 (has links)
To meet the surging water demand due to rapid population growth and changing climatic conditions around the world, and to reduce the impact of floods and droughts, comprehensive water management and planning is necessary. Climatic variability, hydrologic uncertainty and variability of hydrologic quantities in time and space are inherent to hydrological modeling. Hydrologic modeling using a physically-based model can be very complex and typically requires detailed knowledge of physical processes. The availability of data is an important issue to justify the use of these models. Data-driven models are an alternative choice. This is a relatively new and efficient approach to modeling. Data-drive models bridge the gap between the classical regression and physically-based models. By using a data-driven model that relies on the machine learning approach, it is possible to produce reasonable predictions from a limited data set and limited knowledge of underlying physical processes of the system by just relating input and output. This dissertation uses the Multivariate Relevance Vector Machine (MVRVM) and Support Vector Machine (SVM) for predicting a variety of hydrological quantities. These models are used in this dissertation for identifying influential climate indicators, and are used for long-term streamflow prediction for multiple lead times at different locations in Utah. They are also used for prediction of Great Salt Lake (GSL) elevation series. They provide reasonable predictions of hydrological quantities from the available data. The predictions from these models are robust and parsimonious. This research presents the first attempt to identify influential climate indicators and predict long lead-time streamflow in Utah, and to predict lake elevation using machine learning models. The approach presented herein has potential value for water resources planning and management especially for irrigation and flood management.
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A Paleoenvironmental Analysis Using Fossil Insects in Late Quaternary Deposits in Indiana and OhioBergolc, Melanie L. 20 August 2004 (has links)
No description available.
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Ensjön under 200 år : En stratigrafisk studie om vad bevarade kiselalger i sediment kan berätta om klimat och markanvändningFriberg, Olivia January 2021 (has links)
Since 1750, human emissions of greenhouse gases have created a temperature increase, affecting the whole world. Diatoms, single-celled microscopic algae that lives in waters all over the world, have different environmental preferences such as the water depth at which the thrive, salinity, nutrients, pH-values and more. Diatoms also responds quickly to changing circumstances, which makes the suitable as environmental indicators. The purpose of the study is to investigate how the abundance and composition of diatoms has changed during the last 200 years in lake Ensjön, located just south of Norrköping, and to relate those changes both to climate change and known events and environmental factors in the area. The survey is conducted by subsampling sediment cores from which each diatom sample was prepared in accordance with the scheme of Battarbee (1984). The diatoms in the samples were counted under a microscope and the results were analyzed and related to the Cyclotella-Aulacoseira-Fragilaria-theory (CAF) and documented historical events in the local environment. The result of the analysis shows that the composition and abundance of diatoms has changed during the last 200 years, and that this change is due to both climate change (temperature and precipitation increase) and the land-use history of Ensjön. The cahnges in composition of Aulacoseira spp. and Cyclotella spp., where Aulacoseira spp. is expected to decrease, and Cyclotella spp. is expected to increase with a rising temperature, match the CAF-theory for the most part. The change in composition also coincides with several documented environmental factors in the area, especially the change in use of fertilizers and herbicides in agriculture. / Människans utsläpp av växthusgaser har sedan år 1750 skapat en temperaturökning som går allt snabbare, och påverkar hela världen. Kiselalger, encelliga mikroskopiska alger som lever i vatten över hela världen, har olika miljöpreferenser såsom bland annat på vilket vattendjup de trivs, optimal halt av salt, näringsvärden, pH-värden, samt reagerar snabbt på förändrade omständigheter, vilket gör dem lämpliga som miljöindikatorer. Syftet med studien är att studera förändringar i kiselalgernas sammansättning under de senaste 200 åren i den lilla sjön Ensjön belägen något söder om Norrköping och att relatera dessa förändringar till dokumenterade händelser och miljöfaktorer i sjöns avrinningsområde samt till de pågående klimatförändringarna. Undersökningen är utförd genom provtagning av sedimentkärnor från vilka prover preparerades enligt Battarbees (1984) flödesschema. Proverna av kiselalger räknades under mikroskop och sammansättningen analyserades utifrån teorin Cyclotella-Aulacoseira-Fragilaria (CAF) och kända historiska händelser i närmiljön. Analysresultatet visade att kiselalgssammansättningen har förändrats under de senaste 200 åren, och att denna förändring sannolikt kan kopplas både till klimatförändringar (en ökad temperatur) och Ensjöns markanvändningshistoria. Förändringen hos Aulacoseira spp. och Cyclotella spp. följer till stor del CAF-teorin om att det första släktet skulle minska och det andra skulle öka vid en temperaturökning. Vid flera tillfällen sammanfaller förändringar i kiselalgssammansättningen med kända miljöfaktorer i närmiljön, främst i samband med utvecklingen i användningen av mineralgödsel och växtskyddsmedel.
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