Climatic and Hydrological Characteristics of the Liukuei Experimental Forest

六龜試驗林氣象及水文特性之研究

陸象豫(Shiang-Yue Lu) ； 孫銘源(Ming-Yuan Sun) ； 蔡佳彬(Jia-Bin Tsai) ； 黃惠雪(Hui-Hsueh Huang)

《台灣林業科學》 34卷2期 (2019/06) Pp. 71-87

https://doi.org/10.7075/TJFS.201906_34(2).0001

摘要

The Liukuei Experimental Forest (LEF) is the largest experimental forest in Taiwan in which about 10,000 ha of natural and artificial forestlands are administered. To understand the climatic and hydrological conditions of this vast area so as to provide necessary information for forestry management, phenology, hydrology, afforestation, and ecological conservation, the Division of Watershed Management has successively set up 3 second-grade agricultural weather stations in the northern, central, and southern parts of the LEF since 1980 respectively named the Fonkang, Shanping, and Donna stations, as well as 5 gauged watersheds in the Shanping area since 1964. This report summarized the effective electronic records of these 3 stations from 1986 to 2017, and presents LEF's climatic conditions in monthly resolution. Average annual rainfall amounts in the Fonkang, Shanping, and Donna areas were 3429.8, 3435.9, and 3536.1 mm, respectively. The average annual rainfall for the entire area was close to 3500 mm (3467.3 mm), which was much higher than that for Taiwan as a whole (about 2500 mm) and indicates that the LEF receives abundant rainfall. However, rainfall in the LEF mostly occurs in April to October, and this period can be defined as the wet season. Rainfall in the wet season accounted for 92.8, 94.5, and 94.7% of the total annual rainfall for the Fonkang, Shanping, and Donna areas, respectively. This shows that rainfall is extremely temporally unevenly distributed. There are a clear wet season and dry season in the LEF. Numbers of rainfall-days (defined as a day with ≥ 0.5 mm of rainfall) in a year for the Fonkang, Shanping, and Donna areas were 142.5, 135.1 and 126.0 d, respectively. The number of rainfall-days in the northern part of LEF was greater than that of the southern part, while the rainfall amount in the north was less than that in the southern part, indicating that rainfall was more unevenly temporally distributed in the southern part of the LEF. Annual average temperatures in the Fonkang, Shanping, and Donna areas were 16.7, 20.7, and 19.7℃, respectively. The entire LEF area belongs to a cool climate zone, based on the annual average temperature. The difference in annual average temperature is mainly determined by elevation. The average monthly temperature differences for the Fonkang, Shanping, and Donna areas in a year cycle were 7.7 (12.3~20.0), 8.3 (15.8~24.1), and 8.6 (14.7~23.3)℃, respectively. Compared to the monthly average temperature difference of the Fushan, Lienhuachih and Taimali experimental forest of ITRI, the average monthly temperature difference of the LEF was relatively low. The highest monthly average temperature for the entire LEF area was in July, and the lowest average monthly temperature was in January. Average daily temperature differences in January for the Fonkang, Shanping, and Donna areas were 7.04, 6.87, and 6.42℃, respectively; and those of July were 5.73, 6.50, and 7.32℃, respectively. Other meteorological parameters monitored in the LEF were humidity, solar radiation, wind speed and direction, and evaporation. The physical quantities of these meteorological factors are also presented in monthly statistics. In addition, the yearly average temperatures of the air, stream-flow, topsoil at 5, 30, and 50 cm in depth of the riparian zone of Chungliao Creek were 19.53,19.04, 18.99, 19.39, and 19.38℃, respectively, for the monitoring period of 2005~2008. The yearly average rainfall, stream-flow discharge, and base-flow for the period 2000~2003 of the Shanping no. 2 experimental watershed were 3316.5, 2043.1, and 487.3 mm, respectively. It was also noted that stream-flow discharge in the period from November to April mainly originated from deep seepage water and groundwater and was approximately equal to that of baseflow.

關鍵字

Liukuei Experimental Forest ； rainfall amount ； temperature difference ； streamflow discharge ； riparian zone

並列摘要

六龜試驗林為台灣地區最大的試驗林，擁有將近1萬公頃的天然及人工林，為能掌握此一廣大地區的氣候狀況，以供林業經營、物候、水文、育林、生態保育等方面的研究所需，林業試驗所所集水區經營組早在1980年起即陸續在試驗林北中南三區設置了鳳岡、扇平及多納等三座氣象觀測站並於1964年起在扇平地區陸續設置了五座試驗集水區。本報告彙整1986年起至2017年該三測站的有效電子紀錄，以月為單位呈現六龜試驗林北中南三區域的氣候狀況。六龜試驗林鳳崗、扇平、多納三測站的年平均降雨量分別為：3429.8、3435.9及3536.1 mm，總平均年降雨量接近3500（3467.3）mm，高於台灣年平均2500 mm甚多，顯示該試驗林雨量甚為豐富。然而主要的降雨多發生在4至10月（濕季），鳳岡、扇平及多納此期間的降雨量分別佔全年總降雨量的92.8、94.5及94.7%，顯示降雨極為不平均，有明顯的乾濕季之分。鳳岡、扇平及多納地區年平均降雨天數（單日降雨量≥ 0.5 mm）分別約為142.5、135.1及126.0天；而北部鳳岡林區年雨量稍低於南部區域，顯示試驗林南部地區降雨比北部區域在時間分布上較為集中。試驗林鳳崗、扇平及多納三林區的年均溫分別為16.7、20.7 及19.7℃，由年均溫觀之，全境均屬於偏涼的氣候區，而年均溫的差異主要係受海拔高度的影響。鳳岡、扇平及多納全年度月平均溫差分別為7.7（12.3～20.0）、8.3（15.8～24.1）與8.6（14.7～23.3）℃，相較於林試所福山、蓮華池及太麻里等其他試驗林的月均溫差，六龜試驗林月均溫差相對地為低。三林區最高月均溫均以7月為最高，最低月均溫則均為1月份。鳳岡、多納及扇平1月平均日溫差分別為：7.04、6.87及6.42℃；7月平均日溫差則分別為：5.73、6.50及7.32℃。其他與氣候相關且進行觀測的氣象因子尚有：濕度、日照輻射、風速與風向、蒸發量等項目，均以月統計的方式呈現該等氣象因子的物理量。此外，試驗林中寮溪濱水帶亦在2005年至2008年進行溪流水溫、大氣及土壤表層溫度監測測，獲知大氣、溪流水及5、30與50 cm深處土壤的年均溫分別為：19.53、19.04、18.99、19.39及19.38℃。扇平二號試驗集水區在統計期間年降雨、逕流及基流量分別為：3316.5、2043.1及487.3 mm，並獲知在十一月至翌年四月間，溪流水主要源自基流。

並列關鍵字

六龜試驗林 ； 降雨量 ； 溫差 ； 溪流流量 ； 濱水帶