1. Part 2. The watershed inventory

2. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 2 of 19 The watershed inventory The lifeblood of a watershed ecosystem is water. Water movement is affected by many physical, chemical, and biological feature and processes.

3. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 3 of 19 Assessing the condition of a watershed ecosystem and the impacts of management actions on it is an essential first step in watershed management

4. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 4 of 19 The watershed management inventory include ： limat 1.Climate 2.Geology and landform 3.Soil 4.Vegetation and land use 5.Hydrology 6.Social and economic systems

5. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 5 of 19 Climate Solar radiation (W/m 2 ) Degree days ( o C) Maximum/minimum air temperature ( o C) Relative humidity (%) Dew point temperature ( o C) Rainfall amount (mm)

6. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 6 of 19 Rainfall intensity (mm/min) Snow (mm) Snow depth (cm) Snow cover (%) Wind velocity (m/s) Wind direction

7. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 7 of 19 Precipitation Precipitation and interception affect the amount, timing, and spatial distribution of water added to a watershed from the atmosphere.

8. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 8 of 19 Precipitation Hydrologists view precipitation as the major input to a watershed and a key to its water yield characteristics. Ecologists recognize the role of precipitation in determining the type of soils and vegetation that occur on a watershed.

9. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 9 of 19 Three conditions for precipitation 1.The atmosphere becomes saturated 2.Small particles or nuclei are present in the atmosphere upon which condensation or sublimation can take place 3.Water or ice particles must coalesce and grow large enough to reach the earth against updrafts

10. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 10 of 19 Saturation vapor pressure – air temperature relationship Saturation vapor pressure – air temperature relationship A C B Saturation vapor pressure

11. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 11 of 19 Types of precipitation 1.Front precipitation(warm/cold front) 2.Orographic precipitation 3.Convective precipitation

12. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 12 of 19 Measurements of precipitation 1.Standard gauge 2.Storage gauge: 1525-2540mm 3.Recording gauge weighting-type tipping-bucket float device water level digital recording techniques

13. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 13 of 19 Measurements of precipitation   =35-45 o H >1 H View of gauge

14. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 14 of 19 Calculating mean watershed precipitation A B C D ABCD 48106 Arithmetic mean=(4+8+10+6)/4= 7cm

15. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 15 of 19 Calculating mean watershed precipitation Thiessen polygon: A4*0.28 = 1.12cm B8 *0.09 = 0.72cm C10 *0.49 = 4.90cm D6 *0.14 = 0.84cm SUM = 7.58cm A B C D

16. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 16 of 19 Calculating mean watershed precipitation Isohyetal: 4.5 * 0.12 = 0.54cm 5.5 * 0.25 = 1.38cm 6.5 * 0.14 = 0.91cm 7.5 * 0.13 = 0.98cm 8.5 * 0.18 = 1.53cm 9.5 * 0.14 = 1.33cm 10.5 * 0.04 = 0.42cm Sum=7.09 A B C D 10 8 6 4

17. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 17 of 19 Estimating missing data Ratio method Where Pc = estimated storm precipitation for station C (mm); Na, Nb, Nc = normal annual prec. for A, B, and C (mm); and Pa and Pb = storm prec. for station A and B (mm).

18. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 18 of 19 Estimating missing data Double mass analysis 19501960 1970 1980 1990 Accumulated rainfall average for stations H and I Accumulated rainfall at station E

19. Part 2. The watershed inventory: lecture 5. Climate 2005-3-8Watershed management -- 5 19 of 19 Interception Ic = Pg – Th – Sf Where Ic = canopy interception (mm) Pg = gross precipitation (mm) Th = throughfall (mm) Sf = stemflow (mm)