Introduction

GROUND-WATER RESOURCES AND DEVELOPMENT: COASTAL PLAIN REGION ERH JEN CHI–KAOSIUNG, TAIWAN

GROUND-WATER RESOURCES AND DEVELOPMENT: COASTAL PLAIN REGION ERH JEN CHI–KAOSIUNG, TAIWAN

Technical Report No. 47
GROUND-WATER RESOURCES AND DEVELOPMENT: COASTAL PLAIN REGION ERH JEN CHI–KAOSIUNG, TAIWAN

L. Stephen Lau, John F. Mink, Chester Lao
May 1971

ABSTRACT
A 200 square kilometer representative area of the coastal plain of southwestern Taiwan was selected for a cooperative pilot ground-water study to identify and provide methods and knowledge that are essential and appropriate for the evaluation of ground water resources and development in Taiwan. The project was jointly sponsored by the Taiwan Sugar Corporation and the Sino-U.S. Joint Commission on Rural Reconstruction. The work was conducted as a cooperative effort of the personnel of the Taiwan Sugar Experiment Station at Tainan and the Water Resources Research Center, University of Hawaii. The pilot study area is located on a coastal plain intensively cultivated for sugar cane, rice, and other crops and is apparently water deficient. Some surface water is used for irrigation, but ground water is more widely used. Existing basic data pertinent to the study were collected, collated, and evaluated and augmented by data developed by the project. The zone of active ground-water circulation is essentially restricted to a relatively thin very fine to fine grain sand of the Tainan formation averaging 10 meters in thickness. Over most of the project area the aquifer is confined or partially confined by clay except at Nan Tzu where water-table conditions prevail. The aquifer is essentially not continuous over the entire coastal plain. Its permeability averages about 10 meters per day but can be occasionally as high as 200 in the lithic coarse sediments found near the foothill areas. Underlying the aquifer is the Gutingkeng formation which consists predominately of thick dark clays with minor fine sands. This formation is of marine origin and contains residual saline water and exhibits no known evidence of extensive fresh water. Present ground-water development consists of numerous shallow wells, most of them tapping the Tainan Formation. The numerical densities of water wells concentrate in the vicinities of the villages of A Lien and Chu Hu, the area west of Chia Tien, and the areas surrounding Nan Tzu. Contemporaneous sea-water intrusion from coastal areas has not been observed, but the residual saline water imposes a constraint to the quality of the aquifer under stress. Hydrologic budget and supplementary flux computations indicate that the natural ground-water recharge coupled with the existing importation can satisfy the supplementary irrigation water requirements even if the entire arable land in the area is cultivated. Low aquifer transmissivity coupled with high well loss were demonstrated through analysis of pumping tests and operational data. The expected optimum yield for a well field and the attendant drawdown demonstrate that numerous wells of low to moderate yield, carefully designed, constructed and maintained, will be best suited for developing the additional ground water. The terrace and alluvial fan area were recommended for future exploratory studies as were other specific studies for the major aspects of this study: geologic, hydrologic, geochemical, and developmental.