Infiltrometer

Mesurer le taux d'infiltration d'eau dans le sol à un taux d'humidité donné

One of the key information required for smart agriculture and storm water

management is how fast the water get infiltrated in to the soil at various

antecedent soil moisture conditions. Storm water generated from a catchment

is well routed if the portion of the rain which contributes to the runoff is

properly estimated. Infiltration data is the most important parameter required

to estimate the runoff. Precision irrigation scheduling to prevent surface

runoff is best estimated if infiltration rates are known for all soil types in a

farm. Farmers could save a lot of resources if they are aware of the infiltration

rates of their farm soil types.

The traditional way of measuring infiltration rate is time consuming and labour

intensive. One would set up the infiltration measurement gear in the field with

a sealed water tank which works on a principle of marriott bottle which

maintains a constant water head. The falling water level is either measured

manually or by a pressure transducer using data logger. The operator may

need to stay at the site until the test is completed.

Landcare Research has developed the automated, cloud connected and smart

phone driven infiltrometer to measure infiltration rate at any given soil

moisture content. Up to maximum of 5 infiltrometers can be networked to

measure infiltration rates at 5 different locations. Since they are connected to

the cloud by a cellular network there is no limitation of the distance between

devices meaning they can be scattered in a 10,000-ha farm and monitor and

control from one location using a smart phone app.

The basic components of the LCR infiltrometer are, measuring and spare water

tanks, soil moisture sensor to measure varying soil moisture content as water

infiltrates in to the soil, an electrode to sense the water level in the ring,

pressure transducer to measure falling water height and electronics to operate

valves in order to maintain the constant water level over the soil and connect

to the internet via cellular network . The water depth over the soil inside the

container ring is maintained at required level and the falling water level in the

tank and soil moisture content are recorded with time. Infiltration ring size and

the water tank sizes can be selected to suit the soil type and can be written

into data process in the cloud using smart phone interface. For example, clay

soil requires smaller rings as infiltration rate is significantly smaller than sandy

soil. Time series data are automatically recorded on a clod data base and sent

to the users email account using the options given in the smart phone

interface. Historical data are displayed on the smart phone interface as time

series charts. Interactive charts on the smart phone allow one to determine

when to terminate the test, for example when the infiltration rate becomes

steady.

The water tank level, soil moisture content battery voltage are displayed on

the interface as well. A spare water tank could be used to refill the water tank

if it gets empty, which could be activated remotely. For example, sandy soil

requires a lot of water before infiltration rate reaches steady state. The

operator will receive a warning txt message on the smart phone when the

water tank is closer to empty, so the water tank could be activated remotely.

The smart phone interface also provide option to add any field notes for the

location it is installed, for example soil and vegetation types. The basic

procedure to setup a infiltrometer network is to locate them at desired soil

zones, if necessary with spare water tanks and activate and monitor from a

location which is most convenient, for example from your living room.