Click questions to reveal answer:

No. We are acutely aware of the sensitivity of business data we are asking you to input to D-Risk. Therefore, the tool is configured such that no farm level data are stored in the D-Risk computer server once you close the webtool.

Whilst this means that you will have to re-enter your data when you re-visit D-Risk, we have made data entry as quick and easy as possible.

If you would like further information on our Data Protection and Confidentiality polices at Cranfield University then please get in touch at enquiries@d-risk.eu.

An external link above the drop-down list (“see locations”) on the D-Risk interface opens a new window in your browser and takes you to an interactive map on the National River Flow Archive (NRFA) website where you can easily identify the gauging station ID or catchment name.

Ideally, yes, as a surface water licence may still be restricted by emergency drought restrictions, such as Section 57 restrictions in England, which can be included within the D-Risk assessment. If you do not choose the catchment details, you must ensure that the “Include emergency drought restrictions (e.g. S57)” option is not selected.

To avoid excessive data entry, D-Risk assumes that the irrigated crop mix and areas each year remain constant. However, you can easily use D-Risk to evaluate how sensitive your licensed headroom and irrigation deficits are to future changes in crop mix and/or irrigated areas.

Yes, the crops available to choose in D-Risk represent the most common commercial crops for which established relationships between agroclimate and theoretical crop irrigation needs have been developed drawing on previous work by Cranfield University. If you want to assess irrigation requirements for a crop that is not within the list, or a specific variety (e.g. pre-pack potato), then you can choose a crop from the list with similar planting and harvesting dates and modify the “irrigation correction factor” to match your estimated irrigation needs for that crop. For example, if you want to represent turnip, then you can select parsnip and modify the irrigation correction factor to reduce or increase the crop water requirements according to your farm experience. Other crops can therefore be modelled, but you will need to use an existing crop as an analogue and then modify it accordingly.

No, there is no limit to the number of crops or abstraction licences that can be entered.

The analyses within D-Risk rely on specific location inputs provided by the user which are then combined with gridded / catchment weather data that are representative of the area including the farm postcode/ catchment. However, given that every drought event is different and that droughts are infrequent, the weather dataset used in D-Risk also needs to include a wide range of potential drought events, in order to develop a risk-based approach to assessing drought impacts on irrigated production.

D-Risk therefore uses a recently released gridded weather dataset called the ‘MaRIUS event set’ which contains 100 time series of equally probable weather, each of 30 years length. This dataset has been verified against long-term observed weather data from the Meteorological Office. The postcode for the farm site and gauging station ID for the catchment is used to extract the relevant weather data for farm and catchment is located. We have used the MaRIUS event set data in two ways:

  • Firstly, we have assumed that the future probability or likelihood of a given level of irrigation need is based on all of these time series and years - this is equivalent to basing the probability of rolling a given number on a dice on 3000 (100 x 30) throws of the dice. We have termed this analysis as ‘average’ conditions;
  • Secondly, we have assumed that the future probability or likelihood of irrigation need is based on the years in a single time series - this is equivalent to basing the probability of rolling a given number on a dice on just 30 throws of the dice. In this analysis, some of these time series will be drier (or have a greater number of extremely dry years) than others. These ‘driest’ and ‘wettest’ time series then provide an uncertainty boundary (envelope) around the long term ‘average’.

The estimation of theoretical crop irrigation needs in D-Risk is based on previous research carried out by Cranfield University. This research was used by the EA in support of their abstraction licence renewal process to assess what they term “reasonable needs”.

Knox et al. (1996, 2007) derived a set of relationships between annual irrigation need and agroclimate for the range of crops and soil types included within D-Risk. These relationships are implemented in D-Risk, with the annual agroclimate calculated from the weather data for the grid square in which your postcode is located. From these data, and using the relationship corresponding to each combination of crop and soil selected, D-Risk then calculates annual series of theoretical irrigation need. This is the ‘net’ annual need and excludes any additional water that might be needed to account for irrigation inefficiencies (losses linked to storage, distribution, and application).

Readers interested in how these relationships were developed are referred to:

Knox, J. W., Weatherhead, E. K., & Bradley, R. I. (1996). Mapping the spatial distribution of volumetric irrigation water requirements for maincrop potatoes in England and Wales. Agricultural Water Management, 31(1-2), 1-15.

Knox, J. W., Weatherhead, K., & Ioris, A. A. (2007). Assessing water requirements for irrigated agriculture in Scotland. Water International, 32(1), 133-144.

Morris, J., Weatherhead, E. K., Mills, J., Dunderdale, J.A.L., Hess, T., Gowing, D.J.G., Sanders, D., & Knox J.W. (1997) Spray irrigation cost benefit study. Cranfield University.

Yes. The latest version of D-Risk has the functionality to represent HOF conditions on surface water licences. It cannot represent Hands Off Level conditions on groundwater licences but represent the emergency drought 100% mandatory restrictions in abstraction if two consecutive days Qday < Q99.

These are different ways of expressing a HOF. The “Hands Off Flow percentile” is a flow percentile, where the number indicates the percentage of time in the year when the flow is greater a specific flow, indicated by the “Flow threshold (m3/s)”. There are different “Hands Off Flow percentiles” available in the drop down list. If you select any of these, the equivalent “Flow threshold” based on observed flow gets automatically filled in the field. If none of the Flow threshold values represent the actual HOF in your licence or if your HOF is given as a specified river flow rate, then you can enter the flow in “Your actual HOF” and click the Add button. D-Risk automatically calculates the equivalent “Hands Off Flow” percentile by linear interpolation which is displayed in the table below and used for further calculation.

No, it is not mandatory to complete all three fields, but you need to select either a “Hands Off Flow percentile” from the drop-down list or enter “Your actual HOF”. If you select any “Hands Off Flow percentile” from the drop down list; the corresponding “Flow threshold” gets automatically filled in the field. If you know “Your actual HOF”, you can directly enter this without selecting “Hands Off Flow percentile” and “Flow threshold” and the D-Risk automatically calculates corresponding ‘Hands Off Flow’ percentile by linear interpolation.

You can select the ‘Gauging station ID and catchment name’ of the upstream gauging station where you have HOF but, irrespective of whether you want to do a multiple farm or individual farm analysis, you must select ‘Individual farms’ as the ‘Type of analysis’. You can then enter the postcode of your farm or a representative farm among the farm groups – this allows D-Risk to select the weather data for a location outside of the HOF catchment.

In this case you have to convert your actual HOF to an equivalent HOF at the nearest main gauging station. Your local Environment Agency office may be able to advise on this.

You can only select one HOF location per licence in a given D-Risk assessment. However, you can easily carry out another assessment in D-Risk with the alternative gauging station to understand the different controls they exert on abstraction.

At licence renewal, you are usually expected to justify ‘reasonable need’ based on the combination of crops you grow, the areas of each that are irrigated and the soil types on which those crops are grown, as well as the application methods you use. D-Risk can therefore be used to help quantify the ‘reasonable needs’ (depths applied, mm) for your farm taking into account current crop mixes and by combining with the irrigated areas (ha) estimate volumetric irrigation demand (m3). The D-Risk data relates to a ‘design’ dry year, so you can then use this data to compare this theoretical volume against how much you actually abstracted in a recent dry year. You will also need to add in an additional factor to account for net and gross irrigation demand, i.e. how much extra you may have used to account for system inefficiencies. The D-Risk data should be helpful in giving you an indication of how much you could theoretically irrigate with your licence against how much you actually irrigated. If you would like to seek further professional advice, please contact us at enquiries@d-risk.eu

You can use D-Risk to explore how adding new or additional reservoir storage capacity would affect your ‘risk profile’. For example, if you already have a reservoir and storage licence, you can simply re-run D-Risk with a modified total storage capacity. If you do not have a reservoir, you will need to specify the reservoir capacity and either define a new storage licence for your farm (as reservoirs cannot be filled using a licence specified for ‘spray irrigation -direct’) or convert part of your direct abstraction licence/s to storage.

We recommend you to carry out this process several times or iterations to find the storage capacity and storage licence requirements that best address your drought risk. If you would like to seek further professional advice, please contact us at enquiries@d-risk.eu

The upper plots shows the annual probability or risk of exceeding a given level of irrigation deficit and headroom without considering any abstraction constraints imposed by local flow conditions. It assumes that all licensed water is unconstrained so that any irrigation deficit is only a function of annual and daily volumetric licence limits and (any) reservoir storage.

The lower plots takes account of constraints imposed by volumetric licence limits, storage volumes and the local flow conditions, which provides a more insight into the actual drought risks. Providing the two sets of plots allow you to understand the relative importance of constraints due to volumetric licence limits and local river flow conditions to your ability to meet crop irrigation need.

Each grower and business has a unique tolerance of drought risk, so there is no set probability (or risk) threshold that you can use. You should select a probability that has associated deficit and headroom results with which you feel comfortable- however, it is common to use the 5th driest year in 20 (or the 80th percentile probability of non-exceedance) in designing new irrigation infrastructure. You must take into account that the lower you want your risk, the higher the level of investment will be required. Also, remember that while risks can be minimised, they cannot be completely eliminated.

D-Risk uses the specified daily licence limit to limit peak irrigation usage. In this case, whilst the annual licenced volume is sufficient to meet the volumetric demand over the year, the daily licence limit is insufficient to meet peak irrigation demand in the summer.

Yes, the reservoir module in D-Risk takes account of user selected HOF and emergency drought (Section 57) restrictions.

If you are interested in further advice regarding your D-Risk outputs, or you are interested in performing more detailed analysis of your business, please contact us at enquiries@d-risk.eu