Part 2. The watershed inventory

Part 2. The watershed inventory: lecture 5. Climate Watershed management 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.

Part 2. The watershed inventory: lecture 5. Climate Watershed management 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

Part 2. The watershed inventory: lecture 5. Climate Watershed management 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

Part 2. The watershed inventory: lecture 5. Climate Watershed management 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)

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

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

Part 2. The watershed inventory: lecture 5. Climate Watershed management 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.

Part 2. The watershed inventory: lecture 5. Climate Watershed management 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

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

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

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

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

Part 2. The watershed inventory: lecture 5. Climate Watershed management of 19 Calculating mean watershed precipitation A B C D ABCD Arithmetic mean=( )/4= 7cm

Part 2. The watershed inventory: lecture 5. Climate Watershed management 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

Part 2. The watershed inventory: lecture 5. Climate Watershed management 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

Part 2. The watershed inventory: lecture 5. Climate Watershed management 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).

Part 2. The watershed inventory: lecture 5. Climate Watershed management of 19 Estimating missing data Double mass analysis Accumulated rainfall average for stations H and I Accumulated rainfall at station E

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