1998 Fiscal Year Final Research Report Summary
Studies on the variability of the water and material cycle in the forest
| Project/Area Number |
08454126
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Meteorology/Physical oceanography/Hydrology
|
|---|
| Research Institution | HOKKAIDO UNIVERSITY |
|---|
Principal Investigator |
KOBAYASHI Daiji Institute of Low Temperature Science, Hokkaido University, Pro., 低温科学研究所, 教授 (30001655)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TANAKA Yumiko Experimental Forest, Hokkaido University, Edu.Stuff, 農学部・附属演習林, 教務職員 (60221397)
KURASHIGE Yoshimasa Graduate School of Environmental Earth Science, Hokkaido University, Inst., 大学院・地球環境科学研究科, 助手 (20241383)
TACHIBANA Harukuni Graduate School of Engineering, Hokkaido University, Asso.Pro., 大学院・工学研究科, 助教授 (90002021)
URANO Shin-ichi Graduate School of Agriculture, Hokkaido University, Pro., 農学部, 教授 (40096780)
ISHII Yoshiyuki Institute of Low Temperature Science, Hokkaido University, Inst., 低温科学研究所, 助手 (40222955)
|
|---|
| Project Period (FY) |
1996 – 1998
|
| Keywords | Boreal Forest / Water, Energy and Material Cycle / Forest Evapotraspiration / Streamflow Generation / Chemical Constituent / Suspended Sediment / Nutrient / Variability |
|---|
| Research Abstract |
The purpose of this study is to clarify the variability of the water, energy and material cycle in the forested basin, specially in the boreal forest basin. Our findings are summarized as follows :
There are three main results in the forested (sparse mixed-wood) mountainous basin in northern Hokkaido. That is, 1) stream temperatures during the recession flow period were similar to the soil temperature at 1.8 m below the land surface, suggesting that subsurface water contributions to streamflow are derived from this depth ; 2) the solid precipitation accounted for 53% of the annual precipitation and snowmelt runoff accounted for 45% of the annual runoff ; and 3) a sediment supply to the river-bed sediment was most likely to be occurred during the mid-snowmelt season, and active stirring-up of river-bed fines from the newly supplied sediment formed the clear peak of the suspended sediment concentration in mid-snowmelt season.
In a quaternary volcanic ash watershed in the northern temperate
… More
forest zone, the old water contributed the stormflow more than 80% even in a 200mm/48hours-rainfall event. This result was derived from the standard two-component hydrograph separation approach for the silica concentration. As much as 80% of peak runoff suggests that new water displacement with soil wa* occurred immediately during the event.
To understand the runoff characteristics of the nutrient loads from the forest basin, water quality of the four forest streams whose basins are contiguous to each other was observed simultaneously. The principle component analysis of the water quality data of the four streams suggested that the main factors characterizing the water quality of the forest streams are the condition of surface soil layer and the degree of streamflow variation.
To clarify the hydrological characteristics of the forest watershed in cold snowy region, the water balance of Lake Toya and the runoff from its watershed were studied for last 15 years. The stream inflow in the snowmelt season was 20 to 30% of the annual total discharge from the watershed. This high flow rate contributes to maintain the high lake water level in the summer. Less
|
