A computer-assisted desktop is developed for layout design of a concrete gravity dam on the basis of safety and economy. Using a set of regression equations, a dam layout is proposed. With reference to the regression equations and relevant input data, overall dam dimensions are determined by satisfying the stability criteria jointly under usual, unusual, and extreme loading conditions with the desired hydraulic conformity. Among several feasible alternatives, the program enables a designer to select the optimum layout, which corresponds to the minimum total cost of the structure. The method is applied to a case study to examine dimensions of proposed alternatives and to compare them with those of an existing dam.

Generation of evaporation data generally assists in planning, operation, and management of reservoirs and other water works. Annual and monthly evaporation series were generated for King Fahad Dam Lake in Bishah, Saudi Arabia. Data was gathered for period of 22 years. Tests of homogeneity and normality were conducted and results showed that data was homogeneous and normally distributed. For generating annual series, an Autoregressive first order model AR(1) was used and for monthly evaporation series method of fragments was used. Fifty replicates for annual series, and fifty replicates for each month series, each with 22 values length, were generated. Performance of the models was evaluated by comparing the statistical parameters of the generated series with those of the historical data. Annual and monthly models were found to be satisfactory in preserving the statistical parameters of the historical series. About 89% of the tested values of the considered parameters were within the assigned confidence limits

Synthetic unit hydrograph equations for rainfall run-off characteristics analysis and estimation of design flood have long and quite frequently been presented, the Snyder and SCS synthetic unit hydrograph. The major inputs to the Snyder and SCS synthetic unit hydrograph are lag time and peak coefficient. In this study, the methods for estimating lag time and peak coefficient for small watersheds proposed by Zhao and McEnroe(1999) were applied to the Kum river basin in Korea. We investigated lag times of relatively small watersheds in the Kum river basin in Korea. For this investigation the recent rainfall and stream flow data for 10 relatively small watersheds with drainage areas ranging from 134 to 902 square kilometers were gathered and used. 250 flood flow events were identified along the way, and the lag time for the flood events was determined by using the rainfall and stream flow data. Lag time is closely related with the basin characteristics of a given drainage area such as channel length, channel slope, and drainage area. A regression analysis was conducted to relate lag time to the watershed characteristics. The resulting regression model is as shown below: ※ see full text (equations) In the model, Tlag is the lag time in hours, Lc is the length of the main river in kilometers and Se is the equivalent channel slope of the main channel. The coefficient of determinations (r$^2$)expressed in the regression equation is 0.846. The peak coefficient is not correlated significantly with any of the watershed characteristics. We recommend a peak coefficient of 0.60 as input to the Snyder unit-hydrograph model for the ungauged Kum river watersheds

Since South Korea has uneven rainfall and deteriorating water quality, it is imperative to create a comprehensive water resources policy and management. This paper is to adopt a win-win policy for upstream-downstream local governments that have been in water rights-related disputer or conflicts in the process of allocating water and maintaining water quality. The Win-Win Policy can be an integrated river-basin approach. We define the win-win policy, introduce the win-win case of Delaware River and Colorado River in the United States, and suggest the win-win policy for Nakdong River in South Korea. Nakdong River is chosen for this paper because it has more serious problems in preserving water quantity and maintaining water quality.

Local phenomena around bridge piers and abutments are generally considered to be similar, nevertheless the presence of the incoming boundary layer on the side wall in the abutment case generates extra pressure gradients and consequently a more complex vortex pattern. In the literature, experimental data for bridge abutments are relatively scarce; in particular almost no data are available for the time evolution of the scour. In this work we present the results of several long duration (3 days longrightarrow5weeks) clear water scour laboratory tests around bridge abutments; the time evolution of the erosion process is analysed with respect to local and global characteristic values (maxima, volume, hole shape). In particular we analyse the effect of the constriction ratio b/B between the transversal obstacle dimension and the flume width: in many practical situations abutments (or piers) obstruct a significant portion of the channel, so that the average acceleration due to constriction is expected to increase the scour effects of the local acceleration around the obstacle. Measured values for maximum scour are poorly predicted by literature formulas. Scour depths are positively correlated with the constriction ratio, but increases are smaller than expected from literature indications. Experimental results show that models for bridge piers cannot be directly applied to abutments; in particular, time scales for the latter are significantly larger than for piers.

This study presents the estimation of the entrainment velocity of sediment particles from the scour hole. Sediment particles are entrained from the scour hole downstream of hydraulic structures by the turbulent vortices. Mathematical form of the entrainment velocity of sediment particles from the scour hole was obtained using the impulse-momentum equation with given value of the vertical component of turbulent velocity of the line vortex. Also, its probability density distribution was obtained with the results that the probability density distribution of the vertical turbulent velocity followed the normal distribution. Experimental results of the entrainment velocity of sediment particles showed relatively good agreements with theoretical ones.

The project concentrates on an hydrological analysis. The analysis consists of rainfall, infiltration, Determination of runoff and sediment yield. The risque of erosion and the control measures are related to the slopes and land use. Therefore the first approach to erosion must be correct land use based on land classification. Basically there are two types of mechanical protection works; Drainage and Storage. Realization of a drainage system will be very costly and therefore temporary storage is preferred. For farmland in flat areas hardly any measures are needed. For farmland on slopes temporary storage can be effected by applying tillage with ridges within contour bunds. Along roads infiltration pits should be constructed and in areas with houses, the solution to avoid runoff will be water harvesting.