What the “Whole-System, Water Balance Approach” means for Lowland Drainage in BC

Note to Reader:

People learn from stories, and this e-newsletter article is the first in a series that the Partnership for Water Sustainability will publish over time. The series purpose is to reflect on the policy, program and regulatory framework for land and water stewardship in this province.

In our stories, we will pass on knowledge that otherwise might be lost. The series focus will be on the genesis of regulatory objectives and/or requirements in British Columbia.

This first article in the series is about lowland drainage, in particular the “ARDSA criteria”. Ted van der Gulik, formerly the Senior Engineer in the BC Ministry of Agriculture, connects the dots between past, present and future.

ARDSA is the acronym for Agriculture Rural Development Subsidiary Agreement; and ARDA is the acronym for Agriculture Rural Development Agreement.

Looking down at the lowlands in the City of Chilliwack

Looking down at the lowlands in the City of Chilliwack

“More hard surfaces in the uplands means more surface runoff volume is discharging into the agricultural lowlands. This is the real issue,” states Ted van der Gulik, former Senior Engineer, BC Ministry of Agriculture

2007 Freshet in Southwest DSCF0013In British Columbia, agricultural development is often situated in the lowlands, with urban development mostly in the uplands. This article introduces the “ARDSA criteria” for drainage infrastructure design and operation in the agricultural lowlands. It also sheds light on the need to restore watershed hydrology in the urban uplands.

The criteria are essential in protecting the crops (food on the table) from damage caused by excessive durations of flooding and saturation of the roots. If the crops are at risk, then so is the sustainability of the region.

The understanding provided by this article is part of the big picture for the whole-system, water balance approach that underpins “Sustainable Watershed Systems, through Asset Management”.

Genesis of Agricultural Drainage Criteria

Ted van der Gulik_DSC_0586_Sep2015_120p“Many years ago, the province established a set of criteria which determined the level of drainage improvements that were deemed to be acceptable in terms of cost-benefit, and the ability to pay. These have come to be known as ARDSA criteria,” states Ted van der Gulik, President of the Partnership for Water Sustainability in British Columbia. Prior  to retiring from government, he was the Senior Engineer in the Ministry of Agriculture..

“The ARDSA criteria were used to determine the capacity of drainage ditches and pump stations for all ARDA and ARDSA projects that were approved for funding.

“These criteria were developed to provide an adequate level of drainage while keeping the cost of the infrastructure at a reasonable level to be able to achieve a cost-benefit ratio of greater than 1 for the entire project.”

With the Passage of Time…..

“Although reference continues to be made in engineering reports to the ARDSA drainage criteria, there is an absence of recognition of the underlying cost-benefit rationale for the criteria. I believe this reflects a loss of understanding that could have potentially serious implications for current and future decision-making,” states Ted van der Gulik.

Impact of Uplands Development on the Water Balance:

Hillside development in the City of Chilliwack.

Hillside development in the City of Chilliwack.

“One also hears or reads comments that ARDSA criteria are no longer valid and may therefore need to be increased because farmers are seeing more water on their land.

“And why is there more water? The explanation is two-fold. First, our climate is indeed changing. We are experiencing floods and droughts more frequently. In addition, the volume of rain falling during the 5 day 10-year storm is increasing.

“But overshadowing this hydrologic instability is the impact of the uplands development on the agricultural lowlands. Urbanization hardens the landscape. This changes the pre- and post-development annual water balance volume, and its time distribution.

“More hard surfaces in the uplands means more surface runoff volume is discharging into the agricultural lowlands. And the increased flows in streams are over longer durations. This is the real issue.”

Restore Watershed Hydrology in the Uplands:

“The Ministry of Agriculture was an early adopter of the whole-system, water balance approach and the Water Balance Methodology that are at the heart of Stormwater Planning: A Guidebook for BC. This provincial direction resulted from a collaborative effort involving three Ministries: Environment, Municipal Affairs and Agriculture.

“The three Ministries shared this vision for the Guidebook: foster a ‘design with nature’ ethic that, over time, would restore watershed hydrology in the urban regions. To help make this happen, the three Ministries made a long-term commitment (beginning in 2003) to invest in web-based tools and professional development.”

A Path Forward

“Clearly, there is a need to inform and educate a new generation of practitioners and decision-makers about the thinking and the analytical process that resulted in the ARDSA drainage criteria. This would help equip a new generation to make knowledge-based decisions.

“To truly reduce impacts on agricultural lowlands, it would be necessary to restore the watershed hydrology in the uplands. Implement practices that slow, spread and sink rainwater runoff. This would have cumulative benefits, in particular avoided infrastructure costs in the lowlands,” concludes Ted van der Gulik.

To Learn More:

To read the complete article, download  What the “Whole-System, Water Balance Approach” means for Lowland Drainage in BC – Moving Towards “Sustainable Watershed Systems, through Asset Management”

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