One of the key elements in improved management and better planning for aquifer maintenance is the ability to predict changes in aquifer depth. In order to forecast changes in aquifer depth in Qazvin plain, four methods, including Classification and Regression Tree (CART), Reduced Error Pruning Trees (RepTree), M5-Pruned (M5P), and M5Rule, were used in this work. The absolute mean error (MAE) and coefficient of determination (R2) data show that the CART algorithm performs better than other algorithms at forecasting changes in aquifer depth. The CART algorithm's prediction findings showed that the aquifer's behavior in the two seasons was entirely different. In the first stage, which began in November and continued through April, there was an annual average depth of 0.045 m. The aquifer depth has been greatly influenced by rising precipitation and falling air temperature. The aquifer experiences an average decline of 0.15 m in the second portion, which runs from May to October. Aquifer depth has significantly decreased as a result of declining natural water supplies and rising agricultural water use. It is advised to utilize a crop scheme with reduced water need when rainfall reduces due to the strong effect of changes in aquifer depth from rainfall with a delay of one to three months ago.
Sediment cores from Lake Qarun provide a record of mid-late Holocene climatic changes in Northern and Eastern Africa as well as environmental changes due to the activities of ancient Egyptians. We used sedimentological, mineralogical, and geochemical analyses of the cores to investigate long-term variations in lake level due to changing hydrologic inputs. An age model based on three paired 14C and paleomagnetic measurements suggests that the base of the sediment cores is as old as ∼ 5000 B.C.E. Geochemical analyses indicated that lake sediments were derived from Nile floods with an admixture of Saharan sand. Laminated endogenic carbonate-rich clayey silt lithofacies with benthic diatoms are indicative of relatively low lake levels, saline waters and dry conditions; massive lithofacies with planktonic diatom species are indicative of relatively high lake levels, fresh waters and humid conditions. Faintly laminated clayey silt lithofacies suggest intermediate conditions. Variations in lithology as well as diatom composition suggest that the lake level has varied from relatively high levels in its early history to lower levels in later years although there have been numerous cycles in water level over the past 7000 years. A combination of climate changes in the source area of the Nile River as a result of monsoon dynamics; climatic changes in the setting area of the Lake Qarun; and human activities through the dynasties in Egypt produced these variations in lake level. 相似文献
Water Resources Management - Change in the spatiotemporal pattern of precipitation is one the most important effects of climate change. This may result in considerable changes in urban flooding and... 相似文献
This paper contributes to the debate of the efficacy of different patterns of foreign exchange intervention (FXI). Daily data on the Japanese foreign exchange intervention and the Yen/Dollar exchange rates among other macroeconomic variables over the period 1992–2004, in an EGARCH time series model is used to measure the impact of intervention on both the level and volatility of the exchange rate. This paper offers two important results in regard to the effectiveness of the Japanese FXI. First, this study tests whether the pattern of FXI leads to conflicting outcomes with respect to the desired level and volatility of the exchange rates. Second, this study examines the asymmetric impact of the frequency and size of the Japanese FXI on the level and volatility of the exchange rate. This paper finds that successful depreciation of the yen has always been achieved at the expense of higher volatility, a result that supports the conflicting outcomes of the Japanese FXI. In addition, the frequency of intervention is found to be a crucial factor in affecting the level of the exchange rate while the size of intervention is more influential in affecting its volatility. 相似文献
The Dokan Reservoir dam is a concrete cylindrical arch with gravity abutments, located on the Lesser Zab River about 60 km from the city of Sulaimani in north‐eastern Iraq. A bathymetric survey was conducted in November 2014 for a period of 10 days, using an echo sounder of 200‐kHz single beam. The survey results indicated an annual average sediment deposition of 3.8 million m3. Thirty‐two sediment samples were collected from the reservoir bed. The ratio of gravel, sand, silt and clay was 15:14:48:23, respectively. The reservoir bed is covered mainly with silt. The sediments are composed of silty clay (77.6%), silty sandy clay (10%), sandy gravely silty clay (1.2%) and gravely sandy silty clay (1%). 相似文献
ABSTRACT In this paper, the finite element technique used in the analysis and design of water distribution networks will be presented. The method was applied successfully to the solution of three different networks. In order to demonstrate the feasibility of the approach and to show some merits and demerits of the finite element method, a comparison was made on a digital computer with the standard Hardy Cross method. In all cases the finite element method was shown to provide superior performance. Moreover, the programmes were run on three different machines [Wang vs 100, Apple IIe, and IBM micro-computer] to show the effect of increasing storage capacity, machine accuracy, and time saving. 相似文献
Within a two-sector-two-country model of trade with aggregate scale economies and unionisation, a more generous welfare state
in one country increases welfare in that country and can have positive spillover effects on the other. Furthermore, synchronised
expansions of social security are more welfare enhancing than unilateral ones. Our results counter the fears that a race to
the bottom in social standards may result from the ‘shrinking-tax-base’ entailed by international capital mobility. While
affecting trade patterns and income distribution, capital mobility interacts with welfare state policies in increasing welfare,
even when capital flows out of the country that initiates the shock.
This paper obtains an expression of the bias when relevant explanatory variables are omitted in seemingly unrelated regression (SUR) models. A simple demand system is provided to illustrate the direction of the bias terms when a variable is omitted. L'article permet d'exprimer le biais qui résulterait de l'omission de variables explicatives pertinentes dans des modéles de régression sans corrélation apparente (SUR). Le système de demande simple qui est présente ici met en évidence le sens des éléments de biais lorsqu'on omet une variable. 相似文献
In order to assess the quality of the waters of the El‐Kabir River, which forms the border between Lebanon and Syria, water samples were collected for phosphorus (P) and nitrogen analyses at 39 sample stations in the river watershed (18 in Syria, 21 in Lebanon). These samples were collected on the main stem and three major tributaries (Nahr al‐Arous and Nahr Nasrive in Syria, Chadra River in Lebanon). Three major springs also were sampled. The sampling was carried out in September 2001, and January, April and August 2002. Nutrient analyses were carried out on samples taken in September 2001, January and April 2002 in Syria, and in September 2001 and August 2002 in Lebanon. The P concentrations were extremely high throughout the watershed, as were the ammonia‐nitrogen and nitrate‐nitrogen concentrations, indicating extensive pollution. Although the nitrite‐nitrogen concentration was relatively low, it is at the upper end of what might be considered normal, thereby perhaps being indicative of some anthropogenic sources. The spring waters were found to be polluted by nutrients. The nutrient sources contributing to the river pollution were mainly from piped, direct sewage discharges from the many settlements throughout the basin. These were supplemented by diffuse sources directly from agricultural fertilizer use and from the indiscriminate disposal of solid wastes into the river and on the stream banks and lands adjacent to the roads of the watershed. 相似文献