What is regime in irrigation

5b weather conditions

In the 5b weather situation, a cyclone from the Gulf of Genoa pulls in an arc over the Adriatic around the eastern side of the Alps and thus leads "over the back door" to heavy rain in Poland, the Czech Republic, Austria, Germany and eastern Switzerland.

Runoff regime

The runoff regime describes the mean seasonal fluctuations in the runoff of a river, which are caused by precipitation, evaporation, runoff (infiltration, surface runoff) and intermediate storage (snow, ice, groundwater).

The discharge regime is described with the Pardé coefficient of the individual months. The Pardé coefficient is determined from the ratio between the long-term mean runoff in the month in question and the mean annual runoff. The diagrams for the regimes allow a comparison of the seasonal course of the runoff of different rivers. There are 16 different types of regime in Switzerland.


Advection (lat. «Advectio» = approach) describes in meteorology the horizontal approach of warmer or colder or more humid or drier air masses.

For example, when warmer air masses are brought in, they slide over colder air masses and thereby form stratus or layer clouds.


An updraft is a locally limited vertical movement of air, which can be caused by solar radiation, the released heat of condensation in clouds or by the influence of mountains (orographic uplift).

Triggering Event

If the disposition is given, the triggering event sets the dangerous process in motion, for example an intense thunderstorm.

Structural and technical measures

Structural and technical measures reduce the natural hazard by influencing the course of an event (e.g. flood dam, protective wall).


When making snow, snow cannons use water to create technical snow.

With the snowmaking of ski slopes, the snow reliability and thus the profitability in winter sports areas should be maintained or increased even with climate change.

Irrigation needs of agriculture

Irrigation needs include the amount of water without precipitation that is necessary for optimal crop yield.

The need for irrigation depends on the climatic conditions (precipitation, evaporation), the soil water balance and the water needs of the crops. In general, plants can be grown without additional irrigation in areas where annual precipitation is greater than evaporation (rain-fed agriculture). But irrigation is also used in these humid regions, on the one hand for plants that require water (e.g. rice) and on the other hand to bridge seasonal dry phases.


Irrigation describes the artificial supply of cultivated land with water.

Biological measures

Biological measures reduce the risk of flooding by maintaining protective forests or planting erosion-damaged steep slopes and banks.

On the one hand, a small part of the precipitation remains on the vegetation without reaching the ground (interception). On the other hand, plants withdraw water from the soil, which evaporates directly into the atmosphere (transpiration). In addition, rainwater can seep away better in the rooted soil and be better stored temporarily. With the roots, the forest also stabilizes loose material and the bank, which reduces the erosion of fine material and bed load. In the case of continuous rain with very large amounts of precipitation or in the case of heavy precipitation with high precipitation intensity, the forest can only insignificantly attenuate a flood.


Lightning is a spark flashover between clouds with opposite electrical charges or between clouds and the surface of the earth.

The flashing process begins with pre-discharges that build up the discharge channel. The main discharge begins within a few tenths of a second, which in turn is followed by further partial discharges at intervals of hundredths to thousandths of a second. The explosive heating of the air in the lightning channel (within microseconds to approx. 30,000 ° C) causes the subsequent thunder.

Soil moisture

Soil moisture includes the moisture in the soil above the groundwater level, including the water vapor in the pores.

Floor sealing

Soil sealing refers to the sealing of a terrain surface through artificial interventions (e.g. road surface) and as a result of natural processes (e.g. frost), which reduces or prevents the infiltration of rainwater and thus leads to surface runoff.


Drought refers to the persistent lack or a marked lack of precipitation.

Dynamic flooding

In dynamic floods, rapidly flowing water overflows its banks.

Catchment area

A catchment area is a defined area from which all water flows to a specific location.

The drainage of a catchment area is influenced by the following properties: climate, altitude, glaciation, topography, soil, vegetation, geology and shape. These properties also determine the characteristic seasonal runoff distribution of a river, the so-called runoff regime.

Ice grains

Ice grains in clouds are frozen raindrops approx. 1 - 4 millimeters in diameter, which consist of a cloudy ice crystal core and several frozen shells.

During thermal thunderstorms and showers with strong upward and downward winds, ice grains can form hail through repeated accumulation of a water film and repeated freezing.


Evaporation is the transition of water from the liquid to the gaseous state over a water surface or a vegetation-free earth surface.

If plants are involved in the evaporation of water, one speaks of transpiration.


Evapotranspiration comprises the amount of water that reaches the atmosphere through evaporation from the soil as well as transpiration and interception from plants.

Flat printing position

In flat pressure layers, the contrasts in air pressure are so low that no clear pressure centers (high and low pressure) can be identified.

A (thermal) thunderstorm is a meteorological phenomenon that is associated with electrical discharges (lightning) and thunder and is usually accompanied by short and heavy precipitation up to hail.

River straightening

River straightening refers to the shortening of the course of a river through structural measures.

River straightening is often combined with bank construction.

Mountain river

A mountain river is understood to be a larger natural river in the mountains with a steep bed slope in parts, rapidly and strongly changing flow speeds, turbulence and fluctuating amounts of runoff and solid matter.

Mountain rivers and torrents have a high bed slope in parts, which causes a rapidly increasing runoff in heavy rainfall. The high flow speeds increase side and deep erosion.


When it comes to averting danger, attempts are made to reduce the potential danger primarily with structural and technical measures.

Hazard potential

The hazard potential states how intensely and how often a natural hazard can occur in a certain area.

Glacial regime

The glacial runoff regime is shaped by the melting of ice and typically shows a unicodular runoff curve with a maximum in July and August.

Glazio-nival drainage regime

The glacial-nival runoff regime is characterized by snow and ice melt and typically shows a runoff curve with a maximum in June and July.

Global warming

Global warming is the name given to the increase in the average temperature in the troposphere and the oceans that has been observed for 150 years.

Basic disposition

The basic disposition includes the prerequisites for dangerous processes, such as relief, geology, soil and climate, which remain the same over a long period of time.


The groundwater refers to the coherent underground water in solid rock and loose material below the soil layer. The groundwater moves exclusively by gravity.

Renewable groundwater is the portion of groundwater that can be used sustainably, i.e. without impairing its quantity or quality. This proportion varies depending on the region (on average 10% of the available groundwater) and depends primarily on the geology of the subsoil and the presence of rivers.


Permeable, water-bearing rock formations with usable amounts of water.

Groundwater level

The groundwater level defines the height of the groundwater surface or pressure area at a specific location and at a specific time.

The groundwater level is determined by the water level in a permanently installed observation tube (piezometer). While the groundwater level is a measure of the filling level of the hydrogeological system, the spring discharge indicates the natural runoff from this system. Groundwater level and spring discharge depend on precipitation and river infiltration, geology, inclination and thickness of aquifers and human use.


Hail refers to solid precipitation in the form of spherical layers of translucent ice grains (hailstones) with a diameter of over 5 millimeters.

Hail forms in powerful thunderstorms (heat thunderstorms and showers) with strong up and down winds from small grains of ice through repeated accumulation of a water film and repeated freezing.


Flood refers to the condition in a river or lake in which the runoff or the water level has reached or exceeded a certain threshold value.

Inner alpine dry valley

Inner alpine dry valleys are valleys enclosed by high mountains in the interior of the Alps.

They are comparatively dry and warm because the moist air masses rise on the surrounding mountains, rain down there and sink as dry air masses into the valleys.

Integral risk management

Integral risk management is a holistic concept for the sustainable handling of natural hazards that includes all natural hazards and risks, examines all possible measures, includes all those involved in the planning process, takes into account all future developments (e.g. use of space, climate change) and integrates all aspects of sustainability.


Interception is the process by which precipitation is caught by the plant cover and then evaporates without reaching the ground.

The size and thus the effect of the interception depends on the vegetation, the duration and intensity of the precipitation, the wind and the conditions during evaporation.


Isobars are lines of equal air pressure on the weather map.

Annual precipitation

The annual precipitation is the measured amount of precipitation within a year in millimeters.

For the average annual precipitation, the amount of precipitation for a certain number of years is averaged (standard period 30 years, e.g. 1961 - 1990).

Cold front

Cold front is an air mass boundary, behind which a cold air mass follows.

On the cold front, the cold air mass pushes itself under a warmer air mass and quickly displaces it upwards. As it cools down, the water vapor condenses and powerful cumulus clouds form, which can lead to heavy showers.

Karst area

Karst areas consist of limestone and show typical weathering forms such as caves, sinkholes and cart fields.

In karst areas, there is usually a lack of water on the surface, as the surface water quickly seeps away through the numerous fissures and cavities, drains into underground watercourses and emerges again via karst springs elsewhere. Such systems are highly sensitive to contamination.

Karst spring

Karst spring is a spring at which water from a karst area rises to the surface.

Their source discharge can vary greatly, as in karst areas the precipitation and meltwater quickly seeps through the numerous fissures and cavities in the limestone, drains away and then comes back to the surface at the karst source.

Climate scenarios CH2011

The CH2011 climate scenarios are forecasts calculated using scientific models for the climate changes to be expected in Switzerland in the 21st century.

Climate change

The term climate change describes the long-term change in the climate, due to natural or anthropogenic causes.

For global warming observable since the middle of the 20th century, it is extremely likely (95 - 100%) that the anthropogenic influence is the main reason (according to IPCC, 2014).


In meteorology, convection (lat. "Convectum" = carried along) describes the rise of warm air masses into colder ambient air.

Usually convection is generated by solar radiation, which leads to the warming of the ground and the air masses close to the ground. When the rising air reaches the dew point by cooling, clouds begin to form. The formation of cumulus clouds and thunderstorms due to convection can be observed especially in summer.

Concession to use water

A license (Latin “concessio” = concession) from the municipality or the canton is required in Switzerland to use public water.

Torrential rain

Land rain is weak precipitation on the warm front lasting several hours or days.

The rain is long-lasting and not very intense, because the light warm air can only rise slowly and gently over the dense cold air (advection). In the warm air, the water vapor condenses slowly but continuously to form layer clouds.

Long-lasting precipitation, permanent precipitation

Long-lasting precipitation event (several hours to days) with mostly low, little changing precipitation intensity and large spatial extent.

Continuous precipitation is also called advective precipitation, as it is caused by predominantly horizontal air movement (advection).

Multipurpose storage

Multi-purpose reservoirs store water in the meantime in order to achieve several goals, e.g. flood protection, hydropower, shipping, irrigation, fishing, water supply, recreation.

In Switzerland, reservoirs are increasingly being used as multi-purpose storage facilities to compensate for the missing glaciers and decreasing amounts of snow and to coordinate the various usage requirements (e.g. energy industry, agriculture, drinking water supply).

Debris flow

Debris flow (Mure, Rüfe, Laui) is a mixture of water and solids with a solid content (sand, stones, blocks, wood, etc.) of 30 to 60 percent that flows down a torrent at up to 60 kilometers per hour.

Heavy and permanent precipitation as well as intense snowmelt can mobilize existing loose material in the catchment area of ​​a torrent and flow as a water-soaked mixture in the torrent channel or in old slope furrows to the valley. A debris flow causes considerable damage with massive deposits of blocks, debris and wood.

Sustainable water use and management

Sustainable water use takes into account the current and future water demands of society, the economy and the environment on a local, regional and global level.


Sustainability is a concept to secure the current and future demands of society, the economy and the environment on a local, regional and global level.

Natural hazards

Natural hazards include all processes in nature that can be harmful to people, the environment and property.


The amount of precipitation is given in liters per square meter or in millimeters (amount of precipitation). 1 l / m2 corresponds to 1 mm of precipitation.

The amount of precipitation is a volume that falls on a certain area in a certain time. When 1 mm of precipitation on 1 m2 falls, this corresponds to a volume of 1 mm x 1 m x 1 m of precipitation or in centimeters 0.1 cm x 100 cm x 100 cm = 1000 cm3 (= 1 dm3), which corresponds exactly to 1 l.

Low tide

Low water refers to the lowest water level or discharge in a river or lake for a certain period of time.

The cause is a period of unusually dry weather, which is noticeable in the water levels of rivers and lakes below normal height and / or in the decrease in soil moisture and a lowering of the groundwater levels.

Nivales regime

The nival runoff regime is shaped by the snowmelt and typically shows a single-peak runoff curve with a maximum in May and June.

Nutrient input (eutrophication)

Excessive nutrient input (eutrophication) into bodies of water and groundwater can be caused by fertilization (e.g. nitrate, phosphate), livestock keeping (e.g. faeces) or insufficiently treated wastewater.

In eutrophic waters, algae multiply excessively and the oxygen content of the water decreases, so that biological diversity (especially of the fish population) decreases.
Some smaller Swiss lakes in heavily used agricultural areas (e.g. Hallwilersee) have to be kept alive through artificial "lake ventilation".

Surface runoff

Surface runoff is the proportion of precipitation that flows over the surface of the terrain before it reaches a body of water.

Surface runoff occurs when precipitation can hardly infiltrate due to the nature of the subsoil (e.g. rocky areas, compacted soil) (Horton's surface runoff) or after the soil is saturated, i.e. when water can no longer penetrate (saturated surface runoff).

Organizational measures

Organizational measures are measures that are taken in preparation for any events (e.g. emergency plans, monitoring systems, early warning systems, mobile flood protection).

Orographic elevation

Orographic uplift (Greek "oros" = mountain) describes the sliding of air masses on a mountain range.

If moist air masses cool down to the dew point as a result of the orographic uplift, clouds begin to form and congestion can occur.

Pluvial regime

In the pluvial discharge regime, the changing influence of snow, rain and evaporation is shown in a multi-peak discharge curve.


A spring is the place where water naturally comes to the surface from rock or soil.

Spring discharge

The spring discharge describes the discharge of a spring and is usually measured in liters per minute.

The spring discharge is measured as close as possible to the source outlet on a natural cross-section or with the help of an artificial overflow. While the spring discharge indicates the natural runoff from a hydrogeological system, the groundwater level is a measure of the fill level of this system. Groundwater level and spring discharge depend on precipitation and river infiltration, geology, inclination and thickness of the aquifer and human use.

Spatial planning measures

With spatial planning measures, the use of space is adapted to the existing natural hazards in order to reduce the potential for damage.

The hazard map is an important basis for planning appropriate measures to reduce the risk and potential damage caused by floods.

Determination of residual water

Since 1991, water protection in Switzerland has stipulated residual water quantities so that sufficient water remains in river and stream beds below water abstraction. This is intended to secure the diverse natural functions of the waters (e.g. habitat for animals and plants, degradation of pollutants).

For water withdrawals that were approved before 1991, the residual water regulations only apply as soon as the concession to use the water has to be renewed.


In the case of natural hazards, the term risk describes the extent and probability of possible damage.

Risk minimization

When minimizing risk, attempts are made to reduce the damage potential primarily with spatial planning measures, i.e. to adapt the current and planned use of space to the impending natural hazards.

Damage potential

The damage potential describes the damage that could occur to people and property in the event of a possible event.


Showers are short and heavy precipitation from cumulus clouds on the cold front.

Intense showers occur on the cold front, as the dense cold air quickly displaces the light warm air in front of it (advection). In the warm air, a lot of water vapor condenses into mighty cumulus clouds in a short time, whereby the released heat of condensation intensifies the rise of the moist warm air (convection).


Lake is a larger surface body of water with standing or almost standing water that is surrounded by land (inland water).

Most of the large lakes in Switzerland are regulated, which means that the amount of water flowing out of a lake and thus the sea level can be determined. Larger unregulated lakes are, for example, the Boden and Walensee.

Side erosion

In rivers, side erosion removes material from the bank, which can lead to over-gradation and breakdown of the bank areas.

The intensity of the side erosion is determined by the flow velocity, the bed slope as well as the material of the river bed and the banks. In valley rivers, the side erosion outweighs the deep erosion, as the gradient is lower here and the flow speed decreases.

Heavy precipitation, intense precipitation

Heavy precipitation has a high intensity in relation to its duration and occurs rarely, on average no more than twice a year.

Static flooding

During static floods, slow or non-flowing water overflows its banks in flat terrain or along lakes.

Jam effect

Due to the damming effect of mountains, clouds and accumulated precipitation form when air masses flow against them.


Accumulation precipitation (or slope precipitation) occurs when humid air masses are lifted up against mountains and the cooling leads to condensation and thus to the formation of clouds and precipitation.

This orographic uplift of air masses increases heat thunderstorms, showers and land rains considerably and is of great importance for the development of heavy precipitation in Switzerland.


The bisse (French for “bisse”) is an open canal that brings irrigation water from mountain streams or lakes to meadows, fields, orchards and vineyards.

System knowledge

The system knowledge records the decisive processes in a system today and under changed conditions (climatic, socio-economic change).

In transdisciplinary (interdisciplinary) research, scientific and practical knowledge is combined in order to investigate problems in everyday life. A distinction is made between three types of knowledge: target knowledge, system knowledge and transformation knowledge.

Valley river

A valley river has a lower flow velocity than a mountain river due to the lower bed slope.

In the case of valley rivers, lateral erosion outweighs deep erosion, since the flow speed and transport power of the water are lower when the riverbed is low.

dew point

The dew point describes the temperature to which an air packet must be cooled in order for condensation to occur. The humidity at the dew point is 100%.

Deep erosion

In rivers, deep erosion removes material from the bottom of the river, which causes it to be lowered and can lead to over-gradation and breakdown of the bank areas (side erosion).

The deep erosion depends on the amount of water, the bed slope, the flow speed, the bedrock and the type and amount of material transported. A river on solid rock without cargo (e.g. gravel) lacks the grinding material for erosion work. Deep erosion dominates in torrents and mountain rivers with steep gradients and thus high flow speeds.

Transformation knowledge

The transformation knowledge shows how existing conditions can be changed and the measures with which the goals can be achieved.

In transdisciplinary (interdisciplinary) research, scientific and practical knowledge is combined in order to investigate problems in everyday life. A distinction is made between three types of knowledge: target knowledge, system knowledge and transformation knowledge.


Transpiration is the process by which water from plants is released into the atmosphere as water vapor.

The transpiration is an active evaporation, since the plants have to transport the water over roots, trunk or stems and leaves while providing energy before it is released into the atmosphere through the stomata of the leaves.

Drinking water

Drinking water is harmless to health, which is treated as required and fed to households through public pipes.

Around 80% of the drinking water comes from the groundwater, half of which is spring water. The remaining 20% ​​are extracted from lakes.

Drinking water consumption

For drinking water consumption, the consumption of drinking water per person per day or year is generally calculated.

The total drinking water consumption per capita in Switzerland has decreased by over 100 liters per person and day in the last 30 years and is still a good 300 liters today (including trade and industry).
Only 142 liters per person are currently required in the household. If water consumption at work, during leisure time and during holidays is added, this results in around 162 liters per person and day.
Drinking water consumption per capita is falling for various reasons. The population is more aware and household appliances (e.g. dishwashers) have become more efficient. However, a significant part of the savings has been achieved by relocating the water-intensive industry abroad (e.g. textile industry).
(according to the Swiss Gas and Water Association SVGW)

Drip irrigation

Drip irrigation is an economical irrigation technique in which only the amount of water required by the plants is released into the soil in droplets via hoses close to the roots.

The advantages of drip irrigation are water savings, metered fertilization (i.e. less nutrient input into bodies of water and groundwater) and, in arid areas, less soil salinization. The high costs of acquisition and installation are offset by water savings and improved plant growth.


Over-arching refers to the deposition of predominantly coarse solids that emerged from the bed of the river during dynamic flooding.

Inundation, inundation

If the water overflows its banks during a flood and temporarily covers an area of ​​land, this is referred to as inundation or inundation.

Variable disposition

The variable disposition includes the variables that vary over time and depend on the time of day and season, for example the prevailing weather situation or the condition of the soil and vegetation.


Blockage refers to the clogging of a channel by driftwood, debris or other material, so that water and debris build up and can ultimately result in flooding.

Often trees that are carried along get wedged in a narrowing or at a bridge and other material gets stuck.

Heat thunderstorms

A (thermal) thunderstorm is a meteorological phenomenon that is associated with electrical discharges (lightning) and thunder and is usually accompanied by short and heavy precipitation up to hail.

Clouds with a large vertical extension of up to 12 kilometers (cumulonimbus) are typical of thunderstorms. Thunderstorms mainly occur in summer. Heat thunderstorms are triggered by solar radiation and can be intensified by orographic elevation or cold air masses brought in (advection).

Warm front

Warm front is an air mass boundary, behind which a warmer air mass follows.

On a warm front, a warmer air mass slowly and gently slides onto the cold air. The water vapor in the warm air condenses only slowly and layer clouds (stratus clouds) are formed, accompanied by a weak land rain with small drops that lasts for several hours or days.

Water requirement

The water requirement comprises the amount of water that is required by a society for its various needs.

Water management

Water management describes the management of water by humans, whereby an optimal coordination between water supply and water use as well as water consumption is essential.

Water supply

The water supply is that portion of the precipitation that does not evaporate and therefore flows off in streams and rivers and is temporarily stored in lakes, groundwater and glaciers.

Water infrastructure

Water infrastructures include all supply systems for water use and water consumption (e.g. hydropower, irrigation, drinking water supply, wastewater treatment, snow-making).

Water scarcity

Water scarcity denotes a deficit between what is available