Fort, vesting en -onderdelen, Betonnen werken omgeving Fort bij Tienhoven Tienhoven (Stichtse Vecht 26)

English translation

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Description

Cluster 21. Lock, Intake and Check Sluice.

NEW HOLLAND WATER LINE

Introduction

LOCK, INTAKE AND CHECK SLUICE (Kraaienester Sluice), which was intended as a combined civil and military hydraulic engineering component of the inundation works of the New Holland Water Line. The defence system of the New Holland Water Line was primarily based on the controlled flooding of (large) areas of terrain. Controlled inundation required an ingenious system of waterworks, such as sluices, weirs and canals, by means of which the necessary water level could be rapidly set and maintained within narrow limits. Many different types of sluices were applied, depending on the location where they functioned in the system. Sometimes already existing navigation, drainage or check sluices were used, but many new ones were also built or existing ones were substantially adapted. Sometimes local water-level differences between individual polder units had to be bridged by incorporating or using check sluices in existing quays or dikes. For this purpose, schotbalk closures were often applied in waterways or even in coupures in quays, but also so-called outlets with wooden or iron lifting gates or sluices with slides were utilised for this purpose. The Kraaienester Sluice is an existing lock which was adapted for use in the context of the New Holland Water Line to serve as a water intake from the Vecht and as a check sluice. The sluice is currently in use for recreational boating and was restored around 2000 and made suitable for electrical operation by passers-by. Iron ladders have also been incorporated on both sides of the chamber walls. The sluice and the Tienhovensche Vaart are accessible from the Vecht by passage of a brick bridge in the dike along the east bank of the river.

Description

LOCK, INTAKE AND CHECK SLUICE (Kraaienester Sluice), which forms a connection between the river Vecht and the Tienhovensche Vaart (Tienhovensch Canal), which was one of the waterways and drainage routes for the peat areas east of the Vecht near Tienhoven. The sluice possibly dates from the 17th century in origin and was upgraded to some extent in the 19th century when a plan to widen and extend the Tienhovensche Vaart to Huizen and the river Eem was carried out in two phases (1824 / 1838-1869). During this period the canal and the lock also acquired a role in supplying the moat of the Fort near Tienhoven (from 1848-1850) and the inundation of the surrounding area. During this process, presumably around 1880, amongst other things (additional) schotbalk grooves were installed, which after possible water intake and placement of schotbalks could serve as a barrier to inundation water. The brick sluice has an elongated chamber (capacity approximately 30 m), but has on both sides heads placed at a slight angle to the longitudinal axis and also executed considerably narrower than the chamber, which allow passage of up to 3.30 m width. The western heads are slightly higher than the lock chamber; the heads are partly covered with natural stone plates. The sluice is equipped with two sets of wooden gates, of which both southern gates are passable and are provided with an iron grille.

Valuation

The LOCK, INTAKE AND CHECK SLUICE (Kraaienester Sluice) at the mouth of the Tienhovensche Vaart in the Vecht is of general importance because of:

* Cultural-historical values as a component of the New Holland Water Line as designed by C.R.T. Kraijenhoff and initially realised from 1815 by him, Jan Blanken and major-engineer Willem Offerhaus and subsequently strengthened and improved by others over approximately 125 years.

* Architectural-historical values, in particular as an expression of combined military-strategic and civil engineering, which is based on the system of inundation and access defence (19th century).

This is a structure possibly dating from the 17th century and presumably adapted around 1880 for use within the New Holland Water Line with (additional) modifications and related to military-strategic engineering, namely a civil lock sluice with an auxiliary function serving military inundation.

* Ensemble value and situational values as a component of the New Holland Water Line in general and because of the functional and physical coherence with the other components of the complex.

* The component is representative because it underlines and illustrates the application of (civil) sluice works in the functioning of the New Holland Water Line.

* The component is fairly well preserved because the main form, building details and various components have remained recognisable and functional, with the special feature that the heads of the sluice are positioned at an angle to the longitudinal axis of the lock chamber.