Nature-based solutions against wind extremes: Monschauer Heckenland
- domestic hedges (European beech): climatic house protection
- winter: protection against cold wind
- summer: protection against heat (shade)
- field hedges (European beech): protection from grazing cattle and climatic effects
- reduction of wind speed
- reduction of soil erosion
- protection from drying out
- habitats for rodents and resting sites for migrating birds
- provision of fire wood
Snow cover:
- Snow remains at temperature of 0°C until it is melted
Precipitation extremes:
- Heavy rain
- Floods
- Erosion
- Hail (especially on hot summer days with strong convection)
- Drought
Precipitation records Germany and global:
- 8 min: 126 mm (Füssen, 25.5.1920)
- Day: 312 mm (Zinnwald / Erzgebirge, 12.8.2002)
- Month: 777 mm (Oberreute, 1933 / Stein 1954) •
- Year: 3503 mm (Balderschwang / Allgäu, 1970)
- Minute 38 mm (Barot, Guadeloupe, 1970)
- Day: 1870 mm (Cilaos / La Reunion, 15.3.1952)
- Month: 9300 mm (Cherrapunji / India, 07/1861)
- Year: 26461 mm (Cherrapunji / India, 1860/61)
- annual mean: 11684 mm (Mount Waialeale / Hawaii, 1912-1945)
- Lowest precipitation in the long-term annual mean: Dachla Oasis / Egypt: 0.7 mm (1932 - 1985)
Drought:
- Development:
- prolonged absence / reduction of precipitation
- high evaporation
- dry winds
⇒ dehydration of the root zone
⇒reduction of productivity
- Examples drought indices (mainly soil moisture):
- Keetch-Byram Drought Index (KBDI)
- Palmer Drought Severity Index (PDSI)
Artificial rain - cloud seeding:
- Goal: avoidance of damage, especially in agriculture
- “inoculation” of clouds with salts / chemicals (e.g. sodium / magnesium / calcium chloride mixtures)
- small particles: act as condensation nuclei from airplane or ground
- only possible if cold clouds are present
- silver iodide (AgI) to avoid formation of large hailstones by aircraft
- also: major events: e.g. Olympic Games 2008 Beijing
- So far difficult to assess, many questions still open
- other sources: Emission from industrial plants, combustion
Soil erosion by washout and blowout:
- Heavy rain
- Winds
- Washout mainly in low mountain ranges, stepped country, foothills of the Alps
- Blowout mainly in the North German Lowlands
Radiation damage (UV-B):
- DNA damage
- Biomembranes
- Photosynthetic apparatus
- Phytohormones
⇒ e.g. necroses on leaves
⇒ in apple fruit: changes in the skin base color of the fruit, cracking, formation of rotting spots
⇒ sunburn
⇒ possible losses in quantity and quality
Frequency of extremes:
Ecohydrology – Water balance in ecosystems:
Global hydrologic cycle:
Hydrologic cycle on land:
Water balance of a plant stand:
Example: Short weak rain event (beech)
Example: Long rain event with interruption (beech)
- Verdunstungsverlust bei Niederschlägen durch Abgabe von Feuchtigkeit an die Außenluft, besonders im Wald
Compartment apportionment: all events
Throughfall, stem flow, interception:
Importance:
- Important parameters for regional water balancing
- Input for hydrological models (e.g. BROOK90, WaSiM)
- Input for soil erosion assessment and modelling
Water balance in plant stands:
Typical water balance for a Central European forest:
Effects of plant stands on landscape water balance​:
- • interception ⇒ less water reaches the soil ⇒ less discharge
- forest soil = large water storage reservoir ⇒ less and delayed runoff during heavy rains
- forest soil = large water storage reservoir ⇒ more runoff during drought (compared to agricultural or sealed areas)
- vegetation ⇒ less runoff due to transpiration ⇒ Water balance at landscape level: less and more balanced runoff
Evapotranspiration:
- Evapotranspiration bezeichnet in der Meteorologie die Summe aus Transpiration und Evaporation, also der Verdunstung von Wasser aus Tier- und Pflanzenwelt sowie von Boden- und Wasseroberflächen
Runoff​ (Abfließen):
Soil water:
