top of the gl aci o-l acustri ne cl ay Fi gure 8; Sphagnum moss peat

Fi gure 7: Transi ti on between l ake marl s and the

top of the gl aci o-l acustri ne cl ay Fi gure 8; Sphagnum moss peat

Fi gure 6; Varved gl aci o l acustri ne cl ay

Fi gure 3; Borehol e and Sampl e Map Fi gure 4; Li thol ogi cal Uni t Map Fi gure 1; Map of I rel and wi th the catchment

(Charl ton et al . , 2013) Fi gure 2; LI DAR data of the catchment of the ri ver Suck (Charl ton et al . , 2013)

Fi gure 5; Li thol ogi cal Cross Secti on

Genesi s of the Peatl and Ri ver Suck si nce the l ast Degl aci ati on

Genesi s of the research area

- At the end of the Wei chsel i an I rel and was covered wi th i ce whi ch stepwi se retreated to the North duri ng degl aci ati on l eavi ng a seri es of morai ni c ri dges.

- I n mel twater l akes behi nd morai ni c ri dges varved cl ays of 3 mm per l ayer (i g. 6) were deposi ted duri ng some 500 years.

- Duri ng the Late-Gl aci al and earl y Hol ocene (12. 5 - 6 kyr BP) l ake sedi mentati on - Duri ng the Late-Gl aci al and earl y Hol ocene (12. 5 - 6 kyr BP) l ake sedi mentati on

conti nued wi th cal careous gyttj a deposi ts (i g. 7).

- Around 6 kyr BP peat started to devel op (i g. 8) changi ng the ri ver pattern.

Outsi de the ri ver val l ey peat bogs started to devel op.

- Af ter def orestati on f or agri cul ture the sedi ment l oad of the ri ver i ncreased.

Cl ay and si l t l ead to the f ormati on of smal l l evees.

- Si nce the 19 ^th century an i ncreasi ng part of the peat bogs have been excavated.

-

- I n the past 50 years these excavated areas are repl anted wi th mostl y coni f erous trees f or f orestry.

- The recent economi c recessi on has restarted the enhanced peat bog excavati ons.

Introducti on

- I n 2009 the ri ver Suck (i g. 1 & 2) experi enced the hi ghest di scharge ever.

Thi s mi ght have been enhanced by extensi ve peat excavati ons i n the catchment.

- The exact i nl uence of the peat bogs on the hydrol ogy i s however not known, l i ke the composi ti on and hydrol ogi c properti es of the subsurf ace i n the catchment.

Methods

- Fi el dwork i n a key area of the catchment provi ded a l i thol ogi cal map (i g. 3 & 4) and a cross secti on (i g. 5), gi vi ng new i nsi ghts on the genesi s of the ri ver Suck si nce l ast degl aci ati on and a general understandi ng of the catchment subsurf ace.

- Hydraul i c parameters of the subsurf ace have been obtai ned f rom l aboratory tests.

- These parameters are combi ned wi th vari ous data of the Geol ogi cal Survey - These parameters are combi ned wi th vari ous data of the Geol ogi cal Survey

I rel and (GSI ) to make a 3D hydrol ogi cal model f or the catchment.

- The model i s f orced by meteorol ogi cal data (Kl ei n Tank et al . , 2002).

1 Utrecht Uni versi ty, Physi cal Geography Hei del bergl aan 2, 3508 TC Utrecht

2 Nati onal Uni versi ty of I rel and, Geography Maynooth, Room 23C Rhetori c House

*Correspondi ng Contact:

Dr. Wi m Z. Hoek

Mai l : W. Z. Hoek@uu. nl

Ref erences

- Charl ton, R. ; Mackl i n, M. ; Hoek, W. Z. ; Cohen, K. M. ; Gi bson, P. and George, D. Hi stori cal and Hol ocene Dynami cs of an Anastomosed Ri ver i n the I ri sh Mi dl ands. 2013 Bri ti sh Soci ety f or Geomorphol ogy (BSG) conf erence

- Kl ei n Tank, A. M. G. and Co Authors, 2002. Dai l y dataset of 20th-century surf ace ai r temperature and preci pi tati on seri es f or the European Cl i mate Assessment. I nt. J . of Cl i matol . , 22, 1441-1453.

- The Geol ogi cal Survey of I rel and (GSI ); http: //www. gsi . i e/

Hydrol ogi c Setti ng

- Gl aci al morphol ogy coni nes the ri ver Suck and i ts l akes.

- The base of the catchment i l l i s bedrock overl ai n by gl aci al ti l l and ri dges.

- Af ter the degl aci ati on the basi ns were i l l ed wi th i mpermeabl e l ake sedi ments.

- Af ter the basi n was i l l ed and peat started to f orm i n the catchment, the ri ver Suck started to devel op f rom a seri es of l akes to a l ow gradi ent ri ver drai ni ng peat bogs.

- Def orestati on and peat excavati ons i ncreased peak di scharge and sedi ment l oad.

- Def orestati on and peat excavati ons i ncreased peak di scharge and sedi ment l oad.

Further research

- We hypothi se that the f ormati on and excavati on of peat bogs had a maj or i mpact on the hydrol ogy of the ri ver Suck.

- We wi l l test thi s by maki ng a hydrol ogi cal model of the ri ver Suck.

- For thi s model a 3D catchment schemati zati on based on the geol ogi cal data wi l l be - For thi s model a 3D catchment schemati zati on based on the geol ogi cal data wi l l be

establ i shed al ong wi th hydraul i c parameters of the l i thol ogi cal uni ts.

- By runni ng di f f erent scenari os we wi l l expl ore the i mpact of peat bogs and the

excavati ons on the di scharge characteri sti cs of peatl and ri vers.